1 - 3 hours
Very early model ipod4 would not hold a charge anymore. The battery lasted 30 minutes at most.
My very early model ipod4 was ALMOST identical to the repair guide but with some extra bits. Mainly some of the parts were held in with a black rubberized tape that had to be cut to remove parts. Other than that the instructions were right on.
I would say that you have to have experience with this kind of repair and be comfortable working with electronics and the ever-lingering fear that you will break something. You need to be able to tell how much you can push, pull, or flex something and that is just a sense that techy people have.
I was most afraid of the soldering but that was actually very easy. Once I heated the solder pads on the battey cable they came right off very easily, solder and cable together! I was left with a very clean board to solder the new cable to.