I also replaced my recently due to cracked case.
I got mine from this seller and was satisfied with the item condition.

The process was fairly straightforward like others mentioned. The trickiest parts for me are to remove the battery connector and the front-facing camera. I had to yank pretty hard to get the connector detached, harder than what the youtube video shown. Same for the FFC, I was really afraid of tearing the ribbon cable off while squeezing my slot screwdriver (plastic-wrapped of course) underneath the module. Turned out the cable expanded to cover the whole underside of the FFC board so the chance of damaging the board or the cable was practically zero.