I had one as my first AV amp a couple of years ago and it was great for movies - really in your face
On the downside it was very fatiguing for music listening..
Never had a problem with mine overheating or humming on the rear channels.. If it's cheap, ~£100 or so then it's definately worth considering. Anymore than that and you might as well spend £200 on a brand new amp like the Marantz 4200 from Richers..
They heat up more powering at 8ohms than 4 due to less power output at 4 so it depends what speakers you use. I've had mine for years and it is a superb amp it still sounds better than a lot of newer amps. If it's cheap it's worth buying.