The 4S is not "still" having problems, because it has "never" had problems. Some users feel they have a problem with rapid battery drain, but the same problem occurs with the iPhone 4 and iPhone 3GS with iOS 5, which is what you would get if you bought an iPhone 4.
And the same problem has occurred with some phones on iOS 4.x, iOS 3.x, iOS 2.x and iOS 1.x. As far as I can tell the severity of the problem on iOS 5 (based on the number of posts) is no worse than it was with every other version, and it can be fixed if you actually try. Unfortunately, some people would rather whine than try.
Usually i hate all caps in a post, but, GET AN IPHONE 4S.
Seriously. If your getting a device on 2 year contract you are only asking $100 more of yourself to have a better phone for that 24+ months. Whichever one you choose you'd still be spending the same $$$ on the services.
It is already known that issues with the 4S are software "repairable."
The camera is superior on the 4S;
The phone is faster;
You can go to 64GB if you want;
Siri - Hey if you don't love it, don't use it, on the 4S at least you have the option.