The problems with it are a mile long and I'm very disappointed that I upgraded my home machine.
* I run Majordomo2 which is a great mailinglist manager. Not all my mail is getting delivered and I'm getting messages with blank bodies. No one else seems to be having this problem. I'm not sure what I can do now. It could be perl, or worse, it could be gcc which was used to build perl.
* I have a Palm IIIc connected on a serial port. pilot-link woks ok but all software that uses pilot-link (jpilot, kpilot, gnome-pilot) are all unable to connect to the device. No one knows why. I suspect gcc.
* I have a Dell Dimension 4700 at work. The upgrade went fine from Core 3 to 4. Afterwards, I went to start X and it failed. The xorg.conf file was identical both before and after the upgrade, including after running system-config-display --configure. The fix, after a team of people poured 6 hours into it was to not use the VESA driver that it used before. The correct choice is to use the i810 driver. The writeup for it is here: https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=162699
I've had good and bad upgrade experiences before, but this is killing me. My home machine is my domain server and it's been pretty badly crippled because of the mail problems. I can still use my palm but it's a new experience in being crippled.