2 - 5 minutes
My camera lens on the back cover was so scratched that every shot looked like a soft-focus love story from the 70s
Removing the old back glass cover was simple.
There was a little flashing on one of the tabs on the new cover that caught on the milled edge of the aluminum iPhone housing. A couple minutes with a sharp x-acto knife smoothed out the molded tab on the cover, and I got it to fit well.
To take full advantage of the new clear back glass, I stuck a couple stickers *inside* the phone, visible along with the battery and the rest of the iPhone guts.