Mine becomes hot to the point where it's uncomfortable to hold.
It'll heat up when i'm on Twitter or the App Store, just randomly, and the battery life would die fast. Like 99% to 91% in minutes.
So i went to the Apple Store today.
And obviously they can't replace my phone, because they don't have any other 4S in stock! Looks like we're out of luck guys, we have to wait for the next batch to roll in.
Unfortunately, i did a full restore. And that restored all my stats from Day 1, when i got the phone. Therefore the genius didn't have enough info to go by. So a tip to everyone thinking of going to the Genius bar regarding battery life..
do NOT restore your phone right before going.
Anyway, the genius bs'd about how i have too many notifications, or what not. But he did say that if my phone still acts funny to come in later, which i will most likely do.
For now i'm trying to use my phone and not worry about the battery life as much..