I'm the kind of person who believes that Apple's hardware is much nicer than their software, especially when it comes to their Macbooks.
OSX is awesome for most people, but for me I could never get a hang of it. The lack of having a package manager has always been confusing to me. A package manager is very similar to an "App-store" why not have one to keep things simple for developers?
I would have weird Kernel panics with the newest generation Macbook Air, this was very odd, but I don't fault OSX for it.
This is purely a personal preference, but the window management was a very frustrating experience for me. The OSX dock seems so unintuitive for me. If an application is open there's a tiny blue dot to signify that it's open. I can't really explain it, I just don't like it. There were a lot of odd inconsistencies when managing windows in OSX that I can't really remember but would frustrate me.
I'm not really saying OSX is bad, just giving you a perspective from somebody who thought the Mac hardware is much, much better than their software.