I just helped a friend upgrade his system using this mobo - we added a celeron 1.7GHz, 256Mb of Twinmos PC2700 and a Radeon 9500 Pro as well. It took a while to get set up, but even after a couple of days of fiddling I still couldn't get the damned thing to reboot. Whether you tried ctrl-alt-del, rebooting from windows, MS-DOS, or from in the bios, the screen would just go blank and all IDE activity would cease. It feels a bit like a bios issue (I had one version of a bios for my old Asus A7V that gave exactly the same symptoms), but there aren't any more recent bioses out there so I couldn't try flashing to a newer one.
Still, it works fine other than that - just means that instead of rebooting you have to shut down and then power up again. It's got a well-featured bios, and the technical specifications are pretty impressive for the price. Stability-wise, it hasn't really been up and running for long enough to say, but it seems ok - other than that rebooting issue, I can't find anything to fault with it, and hopefully a bios update will deal with that.
Of course, you might not have that problem - it could be due to something else (PSU maybe), and I haven't heard any reviewers complain of anything similar. All in all, thumbs up from me