I installed it over Leopard (ergo no the clean install)
And... No problems (Macbook early 2008). Well, I was expecting an increase in speed for third party apps, though Flock seems slow as hell, but Finder is faster. Preview is a lot faster. Safari is the fastest browser I've used, despite the lack of plug-ins. (Really miss the AdBlock Plus and Personal Web Cleaner)
And quicklook doesn't support a plug-in for List view (Useful for looking into folders)
Start up is not as fast as I thought it would be, but shutdown is faster.
Expose is better though it is a bit buggy, with several windows open, and the bigger icons with the new PDF and everything in Finder. the 64-bit inside makes a difference. Pity that almost none other third party Apps are 64 bit (I'm looking at you, photoshop!)
Hell, I remember setting up a Vista machine last year, and it didn't go as good as this. my own user profile got corrupted, and it crashes if 2 specific user profiles are logged on at the same time. and lets not mention trying to network for file and printer sharing between that and an XP machine.
So no, Depends i suppose on people, their systems and what they do. For me, its gone smoother then I hoped. And it is a fresh release. It can only get better with updates. (And people, check incase your Mac needs Firmware updates from apple. Mine apparently doesn't, and, if memory serves me correct, might be one of the only ones that don't)
