I agree completely that his BH is underrated. Fed's BH is really a beautiful shot to watch. I think most guys here are making fun of his BH because of the fact that Nadal is able to exploit it to no end. However guys, think about it ... how many times Fed ripped so many amazing winners with his BH from almost impossible positions...
... too lazy to post some videos, but I'm sure you know what I'm talking about.
Yes, it is really only Nadal that can consistently exploit Federer's backhand. Djokovic can sometimes, but honestly if Federer is moving too well, Novak can only hurt Federer so much off his backhand, because Federer doesn't necessarily have a problem handling pace from his backhand wing. Plus, the backhand isn't Federer's bread and butter, so what difference would it make if we took his current play style and game while changing his one-handed backhand into a similarly effective two-handed backhand? Nothing really. He would still run around many backhands to hit a forehand, his serve would still be dominant, etc.