Although it was a bit tedious to say the least, replacement of the iPhone battery was actually very easy. There are several step-by-step resources on the internet - YouTube especially that guide you throughout the removal and replacement procedure. You'll need a set of jewelers tools, magnifying device and a very steady hand!! It took me about an hour to complete the job. Be sure to back up the phone first just in case. The new battery seems to last longer than the original in the 3G phone.