i installed it mostly without any trouble... the only trouble i had was having to find an alternate driver for my printer, and also it tends to freeze up and give me the spinning wheel for no apparent reason (i'll have iTunes and Firefox open and when i try to switch desktops it gets all glitchy). otherwise, there's zero difference in the speed of the OS, or pretty much anything else. this release, in all honesty, was totally pointless. they should've kept snow leopard a beta of the next OS, and then once they've done all their fancy UI stuff, release it. i know this will piss off some of the mac superfans, but it's a really pointless upgrade. the only reason i did it is because it cost $9.95 for me.