I wanted to use my old 3g iPhone as an iPod. but the battery would not hold a charge more than a few minutes. I discovered iFixits solution. replacement battery kit, with battery and necessary tools, for a very reasonable price.
Watching the online instructions I determined that I was probably able to do the repair.
The difficulty of repair is marked a being moderate and indicates a time of 15 minutes. Well it took me 30 minutes, but I had no difficulties whatsoever.
I think the secret to accomplishing this repair is to take it slow and easy. Check and double check each step before proceeding. Put the tiny screws in a place where you know what belongs to what.
iFixit is a great DIY site. My next project will be to add an extra drive in my 2009 Macbook Pro, removing the optical laser drive and replacing it with a 1TB hard drive.