I've been running the GM since it was released on my MacBook Pro late '08. Just want to post a few thoughts as helpful advice (random thoughts) as well as to hopefully generate some excitement. 1. I'm really liking Mountain Lion a lot, NOT because of added features or new apps (like Reminders) but because it runs so well. I was all ready to look at getting new hardware because I was counting on Mountain Lion to drag...not so. Best OS performer in a long time. can keep my '08 MacBook Pro a little longer. Highly recommend this upgrade if for nothing else than the performance improvement. And at $19.99, why not? 2. The new dock is nice but not (at this time) easily changed (skinned). If someone knows of an app that allows changes to the dock appearance in ML, I'd love to hear about it. Apps like Dock Library don't work in ML. 3. Overall, app compatibility in my experience is great. Other than Dock Library, all the apps I'm bringing over from Lion work fine (with possible exception of Carbon Copy Cloner, which now has a paid upgrade. Current (not upgraded) version of CCC seems to work, but I can't guarantee it). 4. Do a clean install. Clean install works just like Lion EXCEPT won't fit on standard DVD (need dual layer this time). I personally use USB stick (8GB) and it works like a charm. Use app Lion Diskmaker if you need help with this process (found here: http://blog.gete.net/lion-diskmaker-us/http://blog.gete.net/lion-diskmaker-us/ 5. Try Safari (again). If you've been using Chrome or other browser (like I have) use the version of Safari that comes with ML (at least give it a try). I'm not a real Safari fan but have found it runs much smoother than Chrome in ML. Future updates to Chrome may change all this but for now Safari is the best running browser in my experience on ML. 6. Rejoice that LaunchPad doesn't keep screwing up app order anymore after a reboot. 7. Rejoice that mouse tracking speed with the Magic Mouse doesn't need Magic Prefs anymore to work worth a crap. 8. Get excited that your (even older) computer will run great (at least a lot more smoothly) again and the update is coming your way tomorrow.