iPhone 4S was snapped up like hot cakes during the debut weekend and, according to Apple, it sold 4 million units of the latest smartphone in the first three days after it went on sale on Oct. 14. From June 24-26 in 2010, when iPhone 4 went on sale, Apple sold 1.7 million units during the first three days.

iPhone 4S, the latest iPhone which was unveiled on Oct. 4, only one day before Apple's co-founder Steve Jobs passed away, initially disappointed the fans for they had been expecting the fully redesigned and re-engineered iPhone 5.

When the pre-orders of iPhone 4S went live on Oct. 7, one million units were sold out within the first 24 hours, surpassing the previous single day pre-order record of 600,000 held by iPhone 4 in 2010.

The latest iPhone will be available in 22 more countries by the end of October and more than 70 countries by the end of the year.

What makes iPhone 4S so special? Well, for starters, the new features of iPhone such as Siri voice software and iOS 5 set it apart from Android rivals. Moreover, no one can deny that the death of Jobs also played a great role on iPhone 4S' unprecedented sales volume. The fans probably wanted to get their hands on iPhone 4S to pay tribute for the visionary and creative tech genius.

Here's a review of the top 10 new features of the latest iPhone. Get ready to stand in the line if you want to experience Apple's latest smartphone.