I charged my iPhone 4 fully at 10 am this morning.
It is now at 3%, after spending almost no time using it besides checking Twitter every other hour, as well as Instagram, because I spent almost all day on a MacBook Air. It is now 7 pm.
Heavy use in iOS 5 yielded me with around 40% of my battery charge left after a comparable time.
This is totally unacceptable. Apple needs to fix this asap.