5 - 30 minutos
My battery was struggling with getting through the morning, so I thought it was time to switch it out
I couldn't imagine a better instruction set to go by. I was not very excited about the whole process, since this phone is still fairly new. The process went so smooth I'm thinking of charging my friends a fee to do it for them :)
Be sure to get the iPhone 4 Liberation kit, without it I would have been stuck and not able to get the screws out.