@Tiger - As far as the new OS X specific features go I think I like the notifications Center best. It's really become useful in my day to day. The main reason I upgraded was that I have some apps that had some Yosemite specific updates done to them. Overall I would say Yosemite and all the built-in apps are improved across the board. I don't know what you do with your laptop so I can't say if Yosemite is good for you. If you have a iPhone you might find the "Handoff" feature interesting because it allows you to accept phone calls on your laptop. Although this feature might be more interesting for people who sit at desktops than laptops. If you only use your laptop to surf the web with Safari you might hold off until they make the next incremental update (10.10.1?) because it seems that Safari hangs or slows down from time to time. It does for me and I've read that the symptom affects some others also. Google Chrome on Yosemite does not exhibit this symptom. I would also say that when Safari is not exhibiting this issue it is screaming fast. Maybe faster than Google Chrome. You can read more about the new Yosemite features here: https://www.apple.com/osx/all-features/
