How so? Beyond NVidia having their head up, well, something and releasing crap drivers for the 8600, I really haven't heard much in the way of actual serious problems in the OS to make me see it as any worse then previous 10.x.0 releases. I didn't have some third party kernel hack installed to hose up my upgrade, I have Time Machine running fine off the NAS, and in general have been pretty happy. Am I just lucky in the 3 installs of Leopard I interact with on a daily basis? Nothing I have seen has me running back to 10.4.11.