Hardware

Whats under the hood?
CPU: The iphone 4S has a new dual-core apple A5 clocked at 800 MHz; thats the same as the iPad 2!
The Galaxy S2 has a dual core 1.2 GHz chip.
The S2's processor is faster and can complete tasks faster. Both phones run smoothly and i haven't seen any lag on either phone.
Winner: Galaxy S2