There is no doubt that the Apple iPhone 4S will be the biggest competition for the Nokia Lumia 900 when it joins AT&T's lineup. Nokia and AT&T are going all out in a marketing campaign to make sure the public is well aware of what the Windows Phone platform has to offer coupled with Nokia's newest flagship.
Check out the following video comparison and see how the Lumia 900 and the iPhone 4S fair against each other.
The Nokia Lumia 900 features a 4.3 inch ClearBlack touch display, 16GB of internal storage, an 8 megapixel Carl Zeiss camera with dual-LED flash and is powered, a secondary camera for video calls by a 1.4GHz processor with 512MB of RAM.
The iPhone 4S features a 3.5 inch retina touch display, up to 64GB of internal storage, an 8 megapixel camera with LED flash, a secondary camera for Facetime video calls and is powered by a dual core A5 processor.
source - PhoneArena