The used iphone i purchased was in need of a new battery.
It went well, though, there were a few tense moments. Thought one of the connections was ruined, but from your useful guide, found out you just flip it up, and the ribbon cable comes out WITHOUT the plug. Hmm, took about 1 hour start to finish, well worth it! :)
Read the instructions on ifixit.com very carefully, before diving in. Purchasing the spudger and suction cup well worth the little money they cost. Don't have any images from replacement job, but the phone works fine now.