I have to say I'm also a little disappointed in my 2007 RX350 (Japan built). I bought this off the original owner 2 years ago, and some of the problems have really surprised me. Nothing as major as the OP's (touch wood). Luckily many of them covered under extended warranty, but not all.
VVT mechanism replaced at around 70,000 km
wheel bearing replaced around 70,000km
sunroof deflector rattle - been in 5 times and still no solution (except my own DIY)
various trim rattles (admittedly often as a result of the Lexus service work!)
battery replacement
new front brake pads fitted by Lexus completely worn out within 15,000km
Not quite the reliability I expected from this brand/Toyota. My previous Camry (Australian built) went for 7 years with only a replacement CD player in that time!
This RX seems more akin to my VW GTI's reliability! Well...maybe not that bad
:)