Name features that OS X has that Vista doesn’t? They’re few and far between, I assure you. Especially if you have a stripped copy of OS X like you buy retail.
There’s this much FUD because people got used to MSFT not releasing something new for over 5 years. You can thank a former MS executive for that, as SP2 was supposed to be a new OS entierely.
The dock zooming is actually disabled by default on Tiger and will be on Leopard as well. While older Macs had standalone video acelerators, many many more are getting Intel X3000 and X3100 graphics. This eats into available performance, and also the openGL performance is just horrible on them, not to mention the lack of power effeciency.