Apple's iPhone 4S, the last product created under Steve Jobs, hit the stores on Friday and the pre-orders for the smartphone had been sold out ahead of store launch, reported AT&T, Verizon and Sprint Web sites.

iPhone 4S, which was announced a day before Steve Jobs died, came as a disappointment against the most anticipated iPhone 5, and the phone is not even a big revolution in terms of design.

Though the phone sounds like an incremental upgrade to iPhone 4, it has set a new record of one million pre-orders within 24 hours breaking the old record of 600,000 sales for iPhone 4.

Here's a list of some reasons that makes iPhone 4S people's favorite:

Brand: iPhones are special because they belong to Apple and not any other company. People look at branding as an important value-added aspect of products and services. According to a Reuters report, most of the iPhone 4S buyers are existing Apple customers. Only one out of 10 people surveyed by Reuters was a new Apple customer.

Last Product in Steve Jobs' Signature: Many consumers are buying iPhone 4S as a tribute to Apple's creator, Steve Jobs. I have been waiting for the iPhone 5 for a long time. But since Jobs died, I wanted to make sure I had a new iPhone with some advantages over the old, said iPhone devotee Mark Du.

Processor: Apple's iPhone 4S is equipped with a dual-core processor with an A5 chip similar to iPad 2. The A5 chip has a dual-core ARM Cortex-A9 processor clocked at 1GHz. It's an upgrade to a dual-core PowerVR SGX543MP2 GPU and there's, again, 512MB of RAM in support.

Carrier: Apple's iPhone was selling well even before it reached the carriers like Verizon and AT&T. With Sprint the newest carrier, it is going to offer the best overall plan deal. With the launch of the Verizon iPhone this year, it seems that Apple will support the carrier's 4G network. As Verizon has the potential to reach more than 100 million people with a 4G network, most reports suggest Apple will capitalize on that and bring 4G connectivity to the next Verizon iPhone.

Download Speed: With a high-speed download packet access (HSPA) technology, iPhone 4S has a download speed of twice as fast as that of iPhone 4.

Camera: iPhone 4S has an 8-megapixel camera which has the ability to shoot a more headline and impressive 1080p.

Software: The new phone will come along with Apple's latest operating system, iOS5, which has more than 200 features. The most attractive of the lot is Siri, the voice-recognition system - it answers questions and gives information using natural language and an intelligent understanding of context and phrasing.

Memory: The phone sells for $199 for 16GB of storage, $299 for 32GB and $399 for 64GB, an iPhone flaunting such a memory for the first time.