I've been on Red Hat 9.1(?), Severn, for a few days now and most of it works pretty well.
The big problems I've experienced so far are in the package manager tool and network management tool. The package manager seems to not recognize that the CD containing the RPMs is in the drive and mounted, repeatedly insisting that I put the CD in to install. The network utility hangs my system any time I make an adjustment and I'm forced to reboot. Oh, and the batstat applet crashes when I try to start it. Other than that, things are so far so good.
I guess I should go check Red Hat's Bugzilla to see if any of this is reported :-)