I did have a problem with the driver's side heated seat, but it was fixed while under warranty. And...that's it! No other problems.
The seats could be more comfortable for longer drives, but it's not a major problem.
I love my Lexus RX300! It has been the most reliable car I've ever owned.
I've owned it 7.5 years. Started looking for a new car, but haven't found anything I like better.
My previous car was an Oldsmobile Bravada which started falling apart not long after purchase and service was horrible.
I hope you can avoid the all too common transmission problem with this model.