Shattered ATT iPhone 4 (Concrete), I've done 3g and 3gs repair before, this is more involved by a long shot.
Time: roughly 2 hours
The great parts:
Disassembly and Assembly were flawless, just follow their instructions. Happy with purchase since it comes with warranty.
The not so great:
1.Screen has a yellow hue (very obvious)
2.Still Retina, but if held up to stock screen, you can tell the difference.
3. Gap between glass and side of phone (light leaking through) but may just need more tinkering to fix.
Do not buy Liberation Kit = Phillips screwdriver does not even fit screws in kit, and is too blunt to fit any screws on the phone as well. Better off getting a high quality phillips from a hardware store. At least the pentalobe driver worked.
Magnetized tools are a lifesaver.
After paying close to $130 for tools/screen and getting a close to stock phone, maybe it would have been worth $199 for the replacement.