Not sure about that particular receiver, but for home theater use I've always seen Yamaha as underrated. I use a Yamaha receiver for HT and, in fact, it's the third Yamaha receiver I've had for HT. That one looks very similar to the first one I owned, which served me well.
I can say the Yamaha RX series receivers are built pretty well. I bought a brand new RX-397 just recently, and it's excellent. It's only 50 WPC not the 85 WPC the 770 is, but it's great regardless.
I have a couple of RX-770's, one of which I bought new, the other purchased for a project that never happened. They are nice, and I would say under-rated powerwise. A nice, two channel receiver with some punch!. $60 would be a steal!