One more Linux user here to weigh in. I heard about this from Slashdot as well and decided to give it a shot. I'm running Debian Lenny on an Intel Core 2 Duo with an Nvidia 9500GT video card.
My only two complaints:
1. The installer froze at the end of the install process and I had to kill it manually; however, all the game files installed correctly.
2. There was a weird graphics glitch in a tunnel on the 2nd level of Overture where a sort of "rear view mirror" box appeared for a few seconds. This box disappeared once I left the tunnel.
Other than that, everything ran flawlessly throughout all three games. I literally had no issues whatsoever -- no crashes, no other bugs, no clipping -- everything just worked beautifully. I just finished Requiem about 30 minutes ago and now my mind can return to normal after four days of REALLY strange nightmares
Bravissimo to Frictional for making such a wonderful game, and for porting it to Linux!