I like the OS but most of the highly-touted iApps I could do without.
I use GraphicConverter, not iPhoto
I use Audion, not iTunes
I use Fire or xChat, not iChat
I used iMovie once. I'm not using an alternative, I just don't edit movies much.
I am hanging onto AppleWorks, don't care for iWork from what I've seen of it
Also don't use TextEdit for much (I'm a BBEdit Liter from way back)
I don't use Mail (Eudora rules)
I don't use Safari (although I use Shiira which uses the same web engine)
Never used GarageBand (I don't even get Garageband. What does looping a bunch of prerecording soundstrings have to do with makin' music?)
I do use FileMaker (and make my living developing FileMaker solutions, in fact); FileMaker may not bear the Apple label but it's still a closely connected spinoff of the mother company. Definitely a cool Apple product.
I'm not saying Microsoft's OS comes with better homebrewed apps though. I like Excel a lot but there's not much else from the Redmond house that I care for. If I were a Windows user (ugh), I would use Firefox, Eudora (again), some decent text editor (certainly not Notepad or Wordpad), WordPerfect or WordPro with OpenOffice to deal with other folks' Word documents as needed, ...dunno what I'd use for tunes but it sure wouldn't be Windows Media Player.