I'd call unity more tweakable in that you can get rid of it entirely and replace it with something else. When I was on Ubuntu, I used XMonad, configured to my liking, and no desktop environment. It was great, and better than my experience is today on OSX.

If you know how to, practically any linux distro is much more tweakable than OSX is. Definitely needs a lot more tweaking though, I'll grant that.

Also note that there are people who put linux on their mac book pros, which is something I'm thinking of doing myself.