I too switched from PC to Mac because of OS X and yes, it is a wonderful OS. I was/still am into things like Linux and BSDs on PCs but OS X does what Linux has been trying to do for years - bring Unix to the Desktop.
My only beef is with slow peripheral vendor support. I'm still waiting for HP to release OS X drivers for my USB ScanJet 5400C, and it's mildly annoying that my Cannon PowerShot A5 Zoom doesn't work with the KeySpan adapter I bought (not that I bought it for that purpose, I use my iBook to connect to routers and firewall console ports and the like).
But yes, I can't see why anyone would *want* to run OS9 anymore if they can run OSX.