Recently traded my 05 Acura RL for the 06 with Tech Package. What a great upgrade -- virtually all the bugs worked out and great new technology. Ride and handling seem to be improved with the stiffer, larger PAX tires. Little nits like a warning when lights left on auto and a warning when key leaves the car are fixed. No rattles and no squeaks so build quality seems solid. Navigation appears to be a release later with better graphics and more accuracy.
Navigation system is the best around. Intelligent Cruise control (ACC) is great on the Interstate and definitely works. Ride and handling are supple and predictable. Safest car around -- my insurance cost actually went down from an 05 to and 06.
VTEC engines have a distinct whine that makes them sound not as powerful as the are.