Moving to software is when we find a bigger difference between the handsets. The Iphone 4S comes pre-loaded with IOS 5 whereas the Galaxy S II has Android 2.3 Gingerbread.
IOS is a stable and proven operating system whilst Android has the advantage of a greater degree of customisation. A big difference are the application stores for each handset. The apps for the Iphone 4S are of high quality and more secure, partly because they have to be approved by Apple. We generally found that the Android Market has a lot more apps that aren't worth downloading.
Apple has added a drop down notifications bar to IOS 5 which brings it up to speed with Android. It has also taken the lead in voice activation in the form of Siri which is like a personal assistant on your phone. It understood us better than the Android equivallent and will get even better when location services are added.
Talking about the software on these handsets specifically, we prefer the Iphone 4S. This is largely due to the fact that we're not the biggest fan of Samsung's Touchwiz user interface, which isn't as good as HTC's Sense overlay.
Neither of these phones is going to last for a few days without charging. We found battery life to be a tad better on the Galaxy S II and one of its strong points.
The Iphone 4S also performed well but with notifications turned on the battery drained away uncomfortably fast. For this reason the Galaxy S II comes out on top for battery life.
It's been extremely hard to pick between these two smartphones as they are easily two of the best available today and are very close in many areas.
It was only by a small amount, but the Iphone 4S has won our approval as the better smartphone. It comes with a better display and camera, and performance is also smoother, if only by a small amount. Nevertheless, the Galaxy S II is still a great handset and a better choice if you want the openness and customisation options that the Android operating system offers. µ