I have to agree on the general assessment of iTunes - it's as bloated as a whale that's been beached for a month in the middle of summer.
My problem with the Finder is that it's interface paradigm, with a single menu bar at the top of the screen, is hopelessly outdated and inefficient. I feel like I'm using an OS from the early 90's.
Otherwise, I will say that it runs it's native software beautifully. I have a first generation Intel Mac Mini which only accepts 2GB of RAM, and it runs as a media server and player for my projector without complaints or hesitation, often playing hi-rez media files that my quad-core, 8GB Windows 7 64-bit machine hiccups with. And I've used it occasionally for audio production, with similar results.
So all they really have to do is ditch their user interface and they've got a winner in my opinion ;-)