Upgraded from 2007 RX 350 AWD. Wife's car - she's a lifetime Lexus fan. 2010 model is touted as "totally redesigned," but I think it is more subtle than that. The engine is quieter, gearbox is much smoother, and suspension rework is a big improvement. Others have complained about wind noise, and I seem to agree. Overall, not much disappoints in this new car. Very glad that new rear suspension creates a flatter cargo floor. We're pleased with the upgrade so far. The wife is concerned about the on-demand AWD feature, so we may spend the winter with the Diff locked, which will probably penalize the fuel mileage.
Keyless Access system is good, except it only works on front doors. No sensors on rear doors. Mouse-based Nav system is actually pretty good. Lots of unlocked settings in the computer menus. Large storage compartments. Ventilated seats are OK. On-demand AWD is a good fuel-saving feature.
Add touch sensors to rear doors. 12- speaker sound system upgrade is still very weak. Correct wind noise issues. Add a heated steering wheel. Not too much to say - they improved the existing (and very well received) product line quite well.