After using Fedora Core 9 for some time I feel that I have the right to wine a little bit.
First of all, on my machine it feels rather slow, especially in X. Faster, than Fedora Core 8, so there is some progress, but still not as fast as I would like it to be. I have a pretty decent machine and its performance is quite acceptable in Windows. For instance, Firefox 3 simply flies under Win32, but is dragging under FC. I suspect, that the open-source drivers for my Radeon 9200 are to blame here, but my half-hearted attempts to use the proprietary ATI modules failed. To complicate matters, ATI has stopped support for my chipset, therefore all new releases don't include it.
Packaging lags behind considerably for some reason. For instance, Firefox RC2 has been released, but all we have in releases is beta 5. Boost 1.35.0 has been live for awhile, but only 1.34.1 is available. So I have to roll my own for some of them.
Bottom line - if I had spare time I would consider alternatives, just out of curiosity, but at the moment the problems are not critical so Fedora Core will remain on my desktop in the near future.