My wife and I just picked up an '11 WRX Base here in OR.
Definitely paid off to be informed about invoice pricing (we were able to use USAA for that), and playing dealers against each other.
Got the options we wanted, and the extended warranty stuff we liked for what we wanted to pay.
It was my first new car buying experience, and it turned out to be a bit of a rush.
Plus, it's pretty sweet having one of the first white '11 WRXs around PDX.