Have owned 3 RX 350s - all AWD and all with Navigation. A 2004, 2007 and a 2012. The 2012 model is our favorite in many ways - but all have been 100% trouble free. The snow control - part of the AWD system is amazing.
Shopped extensively online until I came across a certified 2012 RX 350 with 45k miles. Got a great deal ($49k new - mine was $31k), and the vehicle has been superb in most every way. I knew what I was getting into, having read all the reviews, so I was not expecting a sports car like ride. It does what it is supposed to do with silky precision and great reliability. Service costs have been reasonable so far - it is not exciting to drive but it feels as good at 10 mph as it does at 90 mph. I'm anxious to see how it handles in the snow and up in ski country. the controls are intuitive and easy to learn (rain sensing wipers, Bluetooth, nav, sat, etc.) It is a very refined SUV, seems like all the bugs have been worked out. No breakdowns or problems - I'll be putting 200k plus on this one!