20 minutes - 1 hour
My girlfriend found the glass on her Galaxy 4's rear camera shattered.
The repair went very well! Most of the time was spent removing the midframe and motherboard, but all in all it shouldn't take more than 20 minutes. The great news I still have a girlfriend and she's happily taking pictures!
First of all, if you don't plan on buying the recommended tools because you have faith in your own tech toolkit (which I was) make sure you have a screwdriver that will fit Phillps #00 screws, because I didn't realize how small those were, but luckily I had a flathead small enough to remove them. Some more advice I would give is to first of all be careful. Removing the midframe after unscrewing the 9 screws in the back was nerve-racking and tedious. It's fragile and I would definitely recommend buying the plastic opening tool they use in the guide (I didn't but I wish I did haha). I would also recommend being VERY careful removing the motherboard. I don't know if my repair was unique, but the motherboard was fairly difficult to remove. It felt as if it was being caught on something when I tried to remove it, but eventually it came out. Then placing it back in was as much of a pain so just be careful and if this happens, DO NOT try to force it in or out of its slot. Also, when I re-installed the motherboard, the camera I replaced was tilted to one side and I started freaking out, but just push it into place if this happens. =)