I've had the 2008 RDX for just a few days - very impressed so far. Handling and acceleration are great. I'm 6'5" and have over 3 inches of space between my head and the roof - pretty amazing for a car with a moonroof. Initial fit and finish seem perfect. All in all, it's a lot of fun to drive.
Great room in driver's seat. Best stereo I've ever heard in a car. Voice navigation is very cool; not sure yet whether it is a novelty or will be useful longterm. Bluetooth works well with Treo 650.
Better gas mileage. Smaller ignition key (or push-button start).