Il Mio Problema
Old battery did not charge any longer. The computer still worked when plugged but the original battery was gone.
La Mia Riparazione
Super easy. The Mac store person showed me the instructions and video on how to do it. It went without any surprises.
Il Mio Consiglio
Follow instructions to a T. I would put a towel underneath the computer, as it prevents the screws from rolling off the table or surface you are working on, and prevent scratches on the case surface.