I went from the iPhone 4--> the iPhone 5.
My dad went from the iPhone 3GS --> iPhone 4s
I know a bit about both phones.
As stated, the iPhone 5 has a battery issue. Most of the time, it varies from users to users. Its pretty fixable too, some issues were that they restored and older iPhone copy to iPhone 5, most had to reverse this and start fresh on it. I recently updated to 6.1, my battery has improved by 20% and it will last me the entire day just fine.
Iphone 5 is less sensitive. That is true too, but its barely noticeable. I had issues with typing my P and Q because they are on the far edge. once i got used to it, it was fine... the only time u can replicate this sensitivity issue is if you swipe up on the browser like 20 times really quickly, while the 4s will not freeze, the iPhone 5 will... other than that, its not noticeable.
So whats the deciding factor... the question really is, what do u do with your device? do u watch movies on it? Do u view the internet a lot? Do u multitask a lot? Are u willing to pay $300 for a brand new iPhone? if u answered yes to the last 4, the iPhone 5 would be a better choice. if no on the last 4, then the iPhone 4s would probably be better.
some things u may want to consider is LTE. LTE is long evolution, which means its most likely gonna be around for 4-5 years. 4G(aka 3.5G) will be around but its limited... so i guess im trying to say is that the iPhone 5 is better future proofing...