Really? I think in most ways Android and iOS are pretty close these days, but for games Android is probably as far behind as it has ever been. It's a desolate wasteland compared to iOS as far as games go.
It's true that Android has slowly been improving in that area, but the thing is that iOS keeps improving even faster. It seems that for every port that finally makes it to Android, iOS gets hundreds more new good games.
I can't disagree more.. it's still playing catchup in most areas, the only 'new' feature I see is Siri, and quite frankly that's more a gimmick, and it's not like there hasn't been things like Vlingo and others available on Android that whilst not as integrated or exactly the same they have afforded similar functionality when it comes to a lot of Siri offers.
Gaming wise, I also see a shift, all new games tend to be on both platforms, we had a game-a-thon over Christmas as guests had their iPhones, and where showing off all the 'top games' they had bought, and where very surprised that 95% of them where available on Android, and there where free versions of most of them (ad-supported of course)..
And getting back OT.. a lot of Android phones suffer from bloat-ware, my Desire HD now it's modded can last 4 days between charges.. a stock HD (My work colleague has one) struggles to get 1 day out of it.
But, be under no illusion that any smartphone used heavily will only last a few hours, the iPhone 4S is not as good as the iPhone 4 from all the gaming we did over christmas, all phones struggled to do 6 hours non-stop..
I'd just go with whatever OS you prefer, the SGS2 vs iPhone 4s battery wise is just not worth worrying about.
The easiest way around it all is a battery extender or similar, I use a small external pack that takes 4 AA (I use NiMH rechargeables in it) and that will power it for a long time (You can fully charge the phone at least twice, if not more)..