We bought this car used in 2005 from Jim Pattison Lexus Northshore in North Vancouver, BC, Canada. It had been traded in as an ex-lease for a new rx330 by the previous owner 2 days before, and I had to fight off 3 other parties to get at it first. It had full service history and no accidents aside from a few parking lot dings and dents. Aside from what I've mentioned it's been trouble-free, especially in comparsion to the 2001 ML320 my friend bought which has had endless problems.
I thought I had done sufficient research on the RX300 before buying, but only found out about engine sludge and transmission problems after we purchased our car. There are so many posts online about these issues I actually went to my dealer's service department with printouts in hand to ask. They told me they themselves have not had an RX300 come in with a failure related to these issues, but would not deny the problems existed. I also noticed that in their own service schedule (not the one in the owner's manual), it calls for full transmission fluid flushes every 24k kms.
Other non-reliability related issues...
Sometimes I absolutely hate the radio/HVAC controls. Whenever I have a blonde moment I either freeze/bake myself or lose all my station presets.
Turning circle... it's huge! What is up with that?
Power is a little down... I wasn't expected v8 power anyway, but when you pack all the gear and family into it there is some sufferage in performance.
Mileage... I can't do better than 20mpg. I know it's not a little Tercel, but sometimes it really shows, especially with the small gas tank (which they made larger in 2001)... at least it runs on regular unleaded and not premium.
Otherwise we're happy with the RX! The flat floor in the back means I really can have 3 people in the back seat. It handles well for what it is, which is not surprising since it's more car than truck. We never go off-road so that dosen't matter. Brakes are strong, and the ride is nice and quiet. We've had no rattles other than the sunroof shade on occasion when it's open. I know many others here seem to be plagued with issues... are we just lucky?