I took the plunge a few days ago and updated my machines to Fedora 15. The results have been mixed. My netbook and laptop were the first to be upgrades with Intel and Nvidia graphics respectively. Both upgraded fine and the Gnome 3 experience was ok, if a little strange. The problems started with my server with an AMD/ATI graphics. The screen was tearing in places and the smooth experience I was getting on the netbook and laptop had been lost. I still have not fully resolved this problem and it proving difficult to use gnome 3 without it.
The one thing I am finding an issue with in Gnome 3 is the change in panel functionality. I previously minimised some applications like my RSS client to run as a minimised icon. Whilst there is a sort of similar function present I think apps need to be updated to take advantage of it.
Another problem presented itself in the form of a reboot leading to the a message saying the lan cable was unplugged. Rebooting again didn't solve the issue. I had to shut the machine down completely and cold boot before the network stated working again. At least one problem is solved. I will review again once a few more bugs are fixed.