I have been using Leopard since the day of the release, and I have found a few compatibility issues with the programs that I commonly use. I use the GNU Image Manipulation Program (The GIMP) instead of Photoshop because I find it's tool based UI easier to use. Leopard updated X11 to x.org version 7.2, which seems to cause even more short-term compatibility problems. The problem that I have with the GIMP is that anything on the canvas lags a lot. Also, whenever I try to use the paintbrush or pencil tools on the canvas the program crashes. Lastly, a minor complaint but one that applies to X11 as a whole is that the window title bars were not updated to the new Leopard look.
I also use the cocoa beta version of OpenOffice.org for the mac, and with Leopard the icons are no longer transparent, they have a black background. Again, a minor issue, but annoying.
