I have found it to be very good. I have it in use for a number of servers, including one with the commercial version of Zimbra. I like a number of things (e.g. RPM/yum) about Redhat/Fedora better, but I just could not keep up with the project's pace, so I have since moved everything to Ubuntu. I had provided documentation, and a small fix to the skeleton files of Fedora in the past, so I think the project lost a bit more than a user with me.
I really wish Redhat well, so please don't take any of this as anything but my attempt at constructive feedback.