Everyone compares this to win 8 on the fact that it brings in some of the phone UI but I disagree, Metro forces you to use it, you don't have to use Launchpad to launch apps or work in Mountain Lion. I'd say it's just an improved version of lion.
UI response and overall smoothness is MUCH MUCH better in Mountain Lion, even on my old Macbook pro. It's been really nice on my Retina Macbook Pro.
Win Vista = Lion Win 7 = Mountain Lion.
Ya they are off by years, but I'd say Leopard was horrible and was made really smooth with Snow Leopard.
Lion was sorta a pain and is much better with Mountain Lion.
sidenote: Playing Diablo III or HL2 Ep 2 at 2880x1800 just rocks..
in Windows I can play BF3 at 2000+ resolutions too, settings on high except shadows which is at medium.
Love my Retina Mac Can't wait for PC Laptops to adopt a 2880 res.
Windows doesn't look like shit either, works fine with DPI settings.