Smashing Magazine does a good old-fashioned "why OS X is so much better" piece -- ok, well they're not that blatant (it's actually focused on the "top ten usability highs"), but with all of the iPhone/App Store news going around, it's kind of refreshing to see some nice, traditional Mac praise.
So why is OS X better than other (*cough*Windows*cough) operating systems? Metaphors play a huge part -- when you use a Mac, you're not just browsing through files or using plugins, you're flipping through what look like album covers, or pulling up a "Dashboard." And everything is extremely intuitive -- it's clear upon first look at the screen what does what or where to find certain features of the operating system.
Every system has problems, and OS X is no exception. But using it day to day, OS X definitely gives out all kinds of "wait, it was that easy?" and "just works" moments. And that's why we're such big fans of it in the first place.