[wsc981]

I'd agree on Cocoa Touch, but Cocoa seems like a mess to me. I hope Apple will clean up the Cocoa API at some point in the future ...

[alextgordon]

In what way? I find AppKit to be extremely well designed. It has warts, but it's by far the best UI toolkit out there.

[natesm]

My only complaint would be how hacked on Core Animation is in comparison with UIKit. For example, WebView doesn't like having a layer, but this isn't mentioned anywhere in the documentation:

http://developer.apple.com/library/mac/#documentation/Cocoa/...