I drive German, my wife drives Lexus. It's all a matter of personal taste. I appreciate the Lexus because it's well-made and for all the complaints about transmissions and such I spend much less time worrying over and working on the Lexus than any of the German cars.
Oh, and my wife is no soccer mom, she drove a Boxster and an SLK before the Lexus and she prefers the 330 hands down.
Also, if you're comparing the RX330 to the M6 or the 4.6L X5 (cars that are in your sig), then I would hardly call it a fair comparison in terms of handling or power. For what it is, the 330 is a very good machine for the money.
Don't get me wrong, I like Lexus (I just bought one for my wife), but it lacks character, or soul, if you wish. As I live close to Japan, there is 90% ratio of Jap. cars. They are nice, comfortable, reliable, but smth is not there, if you know what I mean. You said you wife drove Mercedes and she didn't like it. I would say MB is totally junk. SLK is poorly built and doesn't look good, compared to Lexus. ( like Germans say: why do you want to buy a MB? It is for old people. Are you old?) But man, BMW is truly an ultimate driving machine. After BMW you can only drive a brand new BMW.
I should not be the ultimate arbiter of automotive taste as my favorite car is still the old '73 VW Thing that I drive whenever I can. Having said that, I've named every German car that I've owned, but I can't quite bond with the Lexus -- I've even told my wife that I looked in the RX's headlights and I did not see a soul, so we agree to a point.