Really though, what's the battery life on an iPhone 4s?

It's the only thing that makes me question whether I should buy one or not.
How often do you guys charge it? Can it at least last the whole day on one full charge?

When you first buy one its battery lasts for a long time. Then it gets shorter and shorter and shorter until you have to charge it two or three times a day. Or you could just buy a new battery and the cycle starts all over again.