Let me first prefix by saying I know Gutsy Gibbon is in beta. So now that we have that out of the way, I have recently upgraded my Ubuntu laptop from Fiesty Fawn to Gutsy Gibbon. For the most part, I am pleased with it, except for a few items. Most of my problems relate to Gnome, X, and ATI drivers.
When I first updated, I got terrible vertical lines on the left and middle of my screen. These were about one inch long and rand the whole length of my screen. After a few hours of messing around with my xorg.conf file, I finally realized that it was not a problem with X, but rather an ATI driver problem. I downgraded my driver by downloading the latest drivers from Feisty Fawn. These seemed to fix the problem. I then started to incrementally upgrade my drivers to xserver-xorg-video-ati_6.7.193-1ubuntu1 which happened to work well. After buzzing around on Launchpad, I noticed Bug #150361. In the details, a developer noted a new version of the drivers (6.7.195-1ubuntu2). I tested these out and they fixed the issue.
Now what happens is whenever I try to play Warcraft 3, randomly the game crashes and the terminal spits out: X connection to :0.0 broken (explicit kill or server shutdown). I can only assume that this has to do with an update to X, which I will probably have to spend some time trying to find out what happened 
. Thus is the life of a beta tester!