Even my grandma could do it, well she is an engineer...
2 - 5 Minuten
Cat pushed it off the coffee table it landed funny and the back glass cracked.
I fix iProducts for my friends all the time but this repair is easer then easy, two screws out slide the cracked back off, slide new one on two screws in, all done. In fact is so easy I did it twice, In all the excitement of having translucent back on iPhone I did not clean all the dast particles from my phone innards so i took it a part cleaned the dast and finger smudges from the inner glass surface and re assembled it again.
Every one I showed it to want see through back now. Even if your phone back pannel is not broken, its so cool (factor x 10) I recommend replacing it.