My biggest gripe is some of the apps, drivers, etc... are not compatible. Some don't work at all, some have limited functionality. Things behave weird (in an unnatural way). Outside of these things so far, the OS is a major improvement. If anything, I would recommend holding off on upgrading just yet for those that haven't. I went back to Snow Leopard for now.
Sorry for the late response but I did not. I have 8gb of ram and would prefer to stay with 64-bit. That said, I'm now on Lion since most of the updates have been done since my original comment. A few minor pains but overall I am okay with it now.
