Apple Inc.'s projection of selling 25 million iPhones by the end of 2011 lends credence from the registered sales of 4 million units of iPhone 4S during the opening weekend.

Apple took the wraps off iPhone 4's sequel earlier this month at its Let's talk iPhone event. The new iPhone 4S has seen remarkable sales numbers during the opening weekend.

Pre-orders for iPhone 4S started on Oct. 7 and has since registered 1 million units on the first day, surpassing the previous single-day record of 600,000 for the iPhone 4.

The latest smartphone from Apple was made available in the U.S., Canada, Australia, United Kingdom, France, Germany and Japan on Oct. 14. The product will be made available on Oct. 28 in Austria, Belgium, Czech Republic, Denmark, Estonia, Finland, Hungary, Ireland, Italy, Latvia, Liechtenstein, Lithuania, Luxembourg, Mexico, the Netherlands, Norway, Singapore, Slovakia, Slovenia, Spain, Sweden and Switzerland.

iPhone 4S comes in either black or white and is available in the U.S. for a suggested retail price of $199 for the 16GB model, $299 for the 32GB model and $399 for the new 64GB model.

The phone is available from the Apple Online Store, Apple's retail stores and through AT&T, Sprint, Verizon Wireless, and select Best Buy, Target and Walmart stores and select Apple Authorized Resellers.

As expected, iPhone 4S featured some important upgrades that were rumored to be a part of the imaginary iPhone 5, like the 1GHz dual-core ARM Cortex-A9 processor, PowerVR SGX543MP2 GPU, an Apple A5 chipset and an 8 megapixel LED-flash camera with 1080p HD video recording. It also has a 3.5-inch TFT Retina multi-touch display and is loaded with Apple's latest Operating System - iOS 5.

In addition, iPhone 4S also comes with alternating antennae for better call reception, CDMA and GSM support, a personal assistant called Siri, iCloud and Bluetooth 4.0 wireless technology.

Apple is facing major competition from smartphones running on Android operating systems, such as Samsung Galaxy S2, Motorola Droid Bionic and the upcoming Samsung Nexus Prime.

Let's take a look at the top 15 reasons why iPhone 4S will trounce Android competitors.

Cool Brand: iPhone 4S comes from Apple, which is known for producing cool devices that appeal to both masses and critics. Meanwhile, branding is being looked by consumers as an important value-added aspect of products or services, as they are expected to come with a certain attractive quality or characteristic.

Apple has now become the world's most valuable brand, and the iPhone 4S is sitting on the glories of its predecessors. The company's brand value has jumped 84 percent to $153.3 billion, driven by the company's success with the iPad and iPhone 4, according to a study published by the global research agency Millward Brown.

Design: Apple products are known for their beautiful design. Despite coming as an upgrade to its previous versions, iPhone 4S boasts a major upgrade to the apps processor, the use of a higher-resolution and more advanced camera module, and the addition of a new cellular radio that makes iPhone 4S a true world phone, according to IHS senior analyst Wayne Lam.

iPhone 4S integrates a five-lens camera module, a first in any smartphone analyzed by the IHS iSuppli Teardown Analysis service. Earlier, the state-of-art has been a four-lens approach.

The smartphone camera module is an autofocus device with an 8-megapixel resolution, compared to 5-megapixel in the iPhone 4 models. Like iPhone 4, the latest phone employs backside illumination technology.

While the form factor of iPhone 4S does not have a bigger screen or thinner body, the processor improvements, HSPA+ speeds (particularly beneficial for AT&T and European subscribers) should drive a large number of upgrades, especially outside the U.S., Jefferies analyst Peter Misek said.

Specs Beefed-up: Apple's iPhone 4S comes with a beefed-up specifications. Apple has fitted an 8-megapixel camera and a dual-core A5 processor with a clocking speed of 1GHz. Though, Android smartphones are also coming with similar features, the huge fan base following the iPhone would help it to navigate the stiff competition.

A5 Processor: The Apple A5 is a package on package system-on-a-chip designed by Apple and manufactured by Samsung to replace the Apple A4. The chip commercially debuted with the release of Apple's iPad 2 tablet, and also powers the iPhone 4S. The A5 contains a rendition of a chip based upon the dual-core ARM Cortex-A9 MPCore CPU with NEON SIMD accelerator and a dual core PowerVR SGX543MP2 GPU.

Apple stated that the CPU is twice as powerful and the GPU up to seven times as powerful as its predecessor, the Apple A4. The A5 package contains 512 MB of low-power DDR2 RAM clocked at 533 MHz.

Improved Graphics: Apple has fitted iPhone 4S with 45nm dual-core PowerVR SGX543MP2 graphics chip clocked at 88 MHz, which is found in iPad 2 to please the gamers. Added to this, the Apple A5 chip performs up to 2 times faster and 7 times faster graphics.

According to Apple, this graphics processor has increased iPad 2's graphics processing speed by nine times compared to the capabilities offered by the A4 processor. According to Anandtech, the 543MP2 has more than twice the compute horsepower of the SGX 535 used in Apple's A4.

Using the published Geekbench scores, Anandtech analysts conclude that Apple is shipping a lower clocked A5 in iPhone 4S than it does in iPad 2 as it makes sense that the phone has a much smaller 5.25 Whr battery. Based on the Geekbench results, it looked like iPad 2 has clocked around 25 percent higher than iPhone 4S, pegging the phone's clock speed at 800MHz.

CVG's deputy editor Andy Robinson told TechRadar that the [iPhone 4S] is certainly laying down some serious credibility for the iPhone as a core gaming device. Not only is it now pushing out games that simply eclipse the [Nintendo 3DS] visually, but features like cloud saving and TV streaming support are really exciting for gamers.

According to Industrygamers.com, Senior Gaming Analyst at Jon Peddie Research Ted Pollak believes the biggest improvement to gaming on the iPhone 4S is the voice control features, noting that one of the features that Nintendogs players loved was the ability to talk to it. There's no reason why a game like that couldn't be done on the iPhone 4S, and much more sophisticated given the voice control shown.

iOS 5: An operating system is the most significant factor considered in the purchase of a smartphone. Apple's iOS is the number two smartphone operating system next to Google's Android.

iPhone 4S runs on the latest iOS 5, which comes with 200 new features including improved notifications system, news stand and iMessage. It will also feature new applications, such as the Reminders app and Newsstand, an application resembling Folders, and iBooks.

Unlike other applications, Newsstand is the first native application to actually run on the home screen. iMessage is an application that allows iPod touch, iPhone and iPad users to communicate, much like a chat service only used between these devices. The iMessage feature has been integrated into the SMS/MMS application used originally on the iPhone models.

iCloud: Apple's iPhone 4S features the new iCloud service in operating iTunes for wireless remote access of music from all computers and mobile devices.

iCloud helps users store photos, apps, calendars and documents without storing them onto the phone's memory storage. Apple also placed itself in top position of the cloud war by inking deals with top music label companies to license songs for the iCloud service.

According to the Los Angeles Times, Apple is preparing license deals with movie studios that would allow consumers to buy movies through iTunes and access them on any Apple device. The service is expected to be launched in late 2011 or early 2012.

Battery Life: A smartphone's battery life is crucial to juice its advanced features. Android phones such as Samsung Galaxy S2 and HTC Sensation offer good battery life. Apple has always scored over competitors in this area by improving battery life with each release of iPhone.

For instance, iPhone 4 has 40 percent more talk time than the iPhone 3GS. iPhone 4 offers 14 hours of talk time on 2G and up to 7 hours on 3G with a standby time of up to 300 hours.

iPhone 4S has a Li-Po 1420 mAh battery, with 8 hours of talk time on 3G networks and up to 14 hours on 2G networks (GSM). According to iFixit, the battery inside iPhone 4S is rated at 5.3 Watt-hour capacity that is slightly more than the 5.25 Watt-hour of the battery used in both iPhone 4.

More Carriers: Already iPhone 4S is available on Verizon, AT&T and Sprint, the three major U.S. carriers, it is expected that the unlocked version of iPhone would be coming in November. After getting the unlocked version, users can power the device on the T-Mobile network.

T-Mobile does not officially vend or power iPhones. However, Chief Marketing Officer Cole Brodman has stated that the network powers over one million unlocked iPhones.

World Phone: Apple's iPhone 4S brings world phone capabilities. This means that each iPhone 4S sold has the hardware to handle both CDMA and GSM networks. So if the user on a U.S. Verizon/Sprint network, and visit Europe, he/she can buy a pre-paid SIM card for a local GSM network, pop it in the iPhone, and avoid roaming fees. The unlocked version of iPhone 4S won't support CDMA networks as they are rare outside of the U.S.

Marketing Expertise: A brand name alone can't sell the product. Marketing is very vital to boost sales and create product awareness. The biggest example is Google Nexus One. Though the phone was listed among the top 10 gadgets of 2010, yet it failed to see success due to lack of effective marketing.

On the other hand, when Apple announces a new device, the company takes to the airwaves describing the new device and showcasing the finer points. iPhone 4S enjoys the privilege.

AT&T's HSPA+ 14.4 Mbps: While the Verizon and Sprint iPhone 4S get typical 3G download speeds, AT&T has faster theoretical downloads on the 4S. AT&T's iPhone 4S does use the same HSPA+ connection as other devices on their network that have been labeled 4G.

iPhone 4S doesn't have 4G technology. The 4G technology is really an advantage only if a user happens to live in a 4G area. Added to this, the problem with 4G network is when a user keeps travelling between 3G and 4G network, the phone always searches for a 4G connection and eats up the battery life in the process.

Until the 4G network becomes more uniform, it's pointless to have a 4G phone. Instead, the user can get a 3G phone that maximizes browsing speeds using HSPA technology. The average consumer won't have any problem with 14 Mbps download speeds and probably won't even notice a difference when streaming.

Siri: Exclusively available on iPhone 4S, Siri comes pre-loaded on the device for use by holding down the home button. Users can give Siri full commands which it will then perform automatically and effortlessly. Apple's virtual assistant Siri can help its users write and send texts, set reminders, schedule meetings, play music, and more.

Apart from this, Siri can do reading/replying to emails and text messages, setting reminders, planning meetings, locating friends, getting maps/directions, and checking the weather. With Siri, drivers will be able to manage many core functions of their iPhones, without even taking their eyes off of the road. Siri's biggest strength is that it allows the user to speak in casual language.

Bluetooth 4.0 technology: A lesser known fact about iPhone 4S is that it is first phone to come with Bluetooth 4.0 technology. Other than this, Apple's MacBook Air and Mac Mini feature the technology.

Bluetooth 4.0 is backward-compatible with all other older versions of Bluetooth, so any existing Bluetooth headsets can be paired with the new iPhone 4S. According to Bluetooth Special Interest Group's executive director Mike Foley, the key new feature of Bluetooth 4.0 is its low-energy technology.

By embedding Bluetooth 4.0 in iPhone 4S, the phone will prove to be a huge stimulus for developers of emerging mobile health devices incorporating low energy technology, according to KnowAboutHealth.com.

Key features of Bluetooth 4.0 technology includes: ultra-low peak, average and idle mode power consumption; ability to run for years on standard, coin-cell batteries; low cost; multi-vendor interoperability; and enhanced range.

App Store: Apple has built a strong ecosystem around its products that makes a consumer loyal to Apple products. For instance, Apple's App Store has more than 500,000 apps that would make iPhone 4S even better. Though Android Marketplace has thousands of apps as well, it still needs to go a long way to match it up with Apple's App Store.