I've owned a Marantz SR5200 for several years now, and with the exception of one problem that was apparently isolated to this particular model (and fixed with no hassle under the company's three year warranty), it's been worry free.
The upside to Marantz stuff is that it looks fabulous and it's built like a friggin' tank. The downside is that Marantz has been very slow to adopt some of the flexibility offered by other companies that has been standard for a while. As an example, it took them quite a while to come around to offering flexible crossover points rather than just the fixed 100hz that I've got on my SR5200.
The sound quality is excellent and I'm sure it's the equal of Denon or HK, but I'm not sure about Marantz' power claims. Mine is supposedly good for 90wpc, but I sincerely doubt that's with all channels driven. Still, it's more than enough power to fill my room, and the SR5200 (SR5500 is the equivalent now, I believe) really is only about halfway up the food chain.
One of the things you'll hear about Marantz is that they've traditionally focused on the sound rather than the bells and whistles. This may or may not be true. I love my receiver, but when the time comes to replace it I might look to Denon for a few more features.
