I have issues with my iPod connection on my new RX 450h also - it is sometimes ok, but I frequently get a "connection fault" message, with no sound or other functionality. I also have an iPhone 3GS which plays music directly onto the Levinson audio system via Bluetooth - perhaps it is crowding out or confusing the software in some way?
Otherwise, I have had my RX 450h SE-L for 3 weeks and overall am impressed. The cabin is a pleasant and really spacious place to be, not least given the RX's relatively compact exterior dimensions. My only moan so far is the surprisinly harsh ride around town - no doubt made worse by the 19 inch wheels. When will premium maufacturers abandon their POINTLESS attempts at *sportiness*...and specify sensible wheel/suspension settings fit for the UK's pothole covered roads? Only Mercedes seem to "get it".