I just installed Fedora Core 9 this morning, after having been a user of FC6 for what feels like years ^^
I have a few issues, but I'll ask about the most annoying one first.
I haven't got any sound (apart from the system beep).
Under FC6 (and perhaps 4, I don't remember that far back), I always had to tell it to use my Audigy soundcard rather than the onboard sound once it had been installed ; it always chose the wrong option. In FC9, I have what seems like it might be the same problem, except that there is no system-config-soundcard, which is what I always used to use to get it working.
I've fiddled with the sound tool under prefs > hardware in gnome, but that doesn't seem to have any effect (and none of the test sounds work).