iPhone 4S, which hits the stores on Friday, has received an overwhelming response. The smartphone got more than a million online preorders in less than a day and its retail launch appears to have set sales records as well.

The smartphone's operating system iOS 5, a new feature called Siri and the introduction of Sprint as one of its carriers could set an exodus of Android phone users. However, it is yet to be determined the percentage of the migration from Android.

iOS 5 comes with more than 200 new features such as the iCloud integration, iMessage, PC-Free Setup and Twitter Integration. The iCloud service is integrated into some key aspects of the iOS 5 - photos, e-books, device backups, document storage and, of course, the iTunes music program. The iMessage is identical in purpose and function to BlackBerry's popular BBM service. PC-Free Setup option will allow users to activate their iDevices without plugging into a computer.

In addition, all back-ups and synchronizations can happen exclusive of any connection to a computer, as long as the user has data stored in the iCloud. Also, the ability to integrate your Twitter account with the iOS 5 is now a reality. Users can share pictures and tweets without having to log in to their Twitter account on multiple occasions.

iPhone 4S has a new feature called Siri which is touted as an intelligent assistant that helps one  get things done just by asking. Siri understands the context, allowing you to speak naturally when you ask it questions, says Apple.

Siri is also claimed to be smart about using the personal information one lets it access. It helps one make calls, send text messages or e-mail, schedule meetings and reminders, make notes, search the Internet, find local businesses and get directions.

The Apple iPhone is available on Sprint also. The addition of Sprint, which has excellent Android-powered phones, in certainly going to help the increase of sales of iPhone 4S.

The phone comes in six models of 16GB, 32GB and 64GB, in black or white. The 16GB model starts at $199 with contract ($649 without), and each additional storage option raises the price up by $100.