Phone wasn't holding charge very well and battery would usually die or go to 3% when working out in the cold (I live in Maine).
The repair was easy I think. I watched a video on it before I tore it apart, which I highly recommend. With all the tools that were provided I was able to get the battery out in about a half hour. Hardest part is heating up the glue that holds the battery in, but the "iOpener" that I also purchased from here helped to heat up the glue enough where I could get the battery out and not heat the phone up too much to where I was melting other parts in the phone (never got even close to melting parts).
My biggest mistake happened when I was peeling off the plastic which was sandwhiching the glue strip that came in the kit.... the strips touched and from there they stuck together and became unusable, so I recommend cutting between them and then peeling the plastic off. Not a big deal though, I just used some strips of double sided tape instead. Other than that everything went smoothly and my phone can hold a charge now!