10 - 15 minutes
I had taken my iPhone to the Apple store and they ran a test and said that my battery had only 40% storage capacity.
The repair went very well, the instructions are very clearly laid out. I did have to use quite a bit of force to lift the screen but I could have also been that I didn't use the smudgers properly.
Careful when lifting the screen, try and work the smudgers more. I just pulled and the screen popped up.