I found that most of OS X worked pretty well and the UI looked good, but when it came down to actually being consistent and productive, it fell over pretty quickly. There were a lot of nuances and rather basic problems which got in the way of literally everything I did from my iPod not playing certain mp3s (very frustrating!) to import and export problems in iWork, automator deadlocking, iCal losing data, Mail sending emtpy messages.
I had some hardware problems as well (not charging and cable fraying after about a month) and while they dealt with them instantly, they shouldn't have occured.
Not a great experience. I've switched to Lenovo and Windows and everything pretty much just works.