I know 8 people total with 360's. Of those, 6 have crapped out and died. The replacements have all been good it seems, except for 1 but the second replacement was something with the cd drive.
The Falcon, Opus and especially the Jasper revision boards pretty much eliminated the issues with earlier boards (named Xenon and Zephyr respectively).
But as far as issues to do with the red ring of death (which was caused by overheating/inadequate cooling) they're pretty much sorted now.