The iphone is constantly pulling data. your location, searching for cell towers and then if you have lots of notifications turned on that will drain the battery. The new iOS is nice as it lets you customize the notifications per app but if you dont know this, it can be a serious battery drain.
Im not impressed with the new iOS due to all the glitches and me having to solve these issues with customers. Seriously, I never met so many adults that act like 2 yr olds. People expect a lot more out of technology than what is available or for the price point. I really tire of hearing people whine about how they paid 200 bucks for the phone. Its like..umm...that is because you are under contract, the phone actually costs double that.
IMO, you pretty much need to charge that baby every night. Some can go a whole day and others last till 5 p.m. It just depends on usage.