Apparently Apple claims 200 new features but I think that includes many as improvements. I don't use iCloud at all and during install they give you a 'Set Up iCloud' panel and all you do is uncheck that box if you don't want iCloud.
With Gatekeeper, ML gives the Mac better security than ever (which is not saying much; you should add third-part security). But I use Snow Leopard all the time and just fool around with these later editions of OS X on another partition.
