20 - 30 minutos
My iPhone 3GS had been having battery problems and all of the sudden wouldn't take a charge at all. I assumed the battery needed to be replaced as that seemed to be the source of the issues I was having.
The repair was straight forward though and the steps I needed to follow were dead on. It was an awesome guide!
It turned out my problem wasn't solved with the battery replacement. I needed to replace the dock connector. Who knows if the battery was actually bad but I put it out there so you can take your pick. This was the cheaper of the two options...
I highly recommend purchasing the suction cup if you don't have a good one because, like others have said, it takes A LOT of force to get the glass to come up. Also, like others have said, make sure you're careful of the antennae (not to break it off) and also of the clip holding the camera in (not to lose it when the screw is removed).