Have a dressed up RX330 with navigation. Have been very impressed with quality, comfort, quiet ride, performance, handling. Have talked with friends who've driven Lexus for 20 years and never needed a repair. Dealership was great, service is great, car is fun to drive. My wife is primary driver, and I thought I would never get her out of her Land Rover (she has a phobia about running into a deer). After one day in the Lexus, she's never gone back to the Land Rover, and will probably buy Lexus from now on. Only complaint: not enough storage bins in front (no place for parking/toll change). Could take a lesson from the Toyota Sienna XLE. Could use parking sonar, too.
Navigation; styling; ride quality; performance (though I'm running at risk of a speeding ticket -- the car is so quiet, you forget how fast you're going). Top of the list: quality. Price is also great for the quality of the car. Friends have moved from Mercedes to Lexus without regret.
Add 5-point parking sonar (front/rear corners, rear center). Add standard laser-guided cruise control. More storage in front seat, esp. something for toll/parking change. Rear climate control would be great. Cooled seats in addition to heated. Ability to watch DVD on navi screen when parked.