I'm a Windows guy temporarily using a Mac to write an iPad app, and the main thing that bugs me about OS X is how fuzzy the fonts look. In Windows, my fonts look ultra sharp on-screen; on Mac, fonts look fuzzy. Apparently it's because of this: http://www.codinghorror.com/blog/2007/06/font-rendering-resp...
But I say to Apple: unless one's monitor has the dot pitch of the iPhone "retina display", your font rendering looks really fuzzy. <rant>What good is "preserving the typeface design" if it makes your eyes water?</rant>