I traded an '05 TSX for the RDX - needed more room for gear. Not only is the RDX just the right size, it's actually MORE fun to drive!! The SH-AWD system produces such grip and control that it almost feels like you're driving a sports car. I've had no problems/repairs, the mileage is acceptable for an SUV (about 21 mpg), and the fun factor is a 10! The ride is firm, but comfortable. The interior is great (and versatile), the technology package is great.
A little better mileage (it's a 4-banger, after all), auto passenger seat, better nav data (it's outdated and finds stores/places 1000 miles away before local ones), a little racier exterior to go with the performance.