Dropped my iPhone on the sidewalk, back shattered. Although the clear packing tape held it together, I realized that it wasn't going to make it long term. So I looked to IFIXIT.
Disappointingly easy. (I'm a techie nerd, and was prepared to do battle if necessary. In fact, I get a lot of pleasure from figuring things out.) But...
I took out the two screws, slid the back off, slid on the new one and replaced the two screws. I didn't record the time, but it was well under 7 minutes (with a bit of time looking inside my phone...)
You don't need *any* techie skills for this repair.