Have now had my GS 350 AWD for 3 months. Beautiful ride. Smooth as butter, but when floored, one is thrown delightfully back into the seats. I test drove Acura and Infiniti, and there was no comparison in terms of the ride quality (although both were cheaper). The AWD provides superb handling in wet conditions. I have had no noise or rattling problems that others describe. The default surround sound system is superb (I sampled the ML system and would've gotten it if I truly thought there was a difference).
Bluetooth phone system, keyless entry and ignition, acceleration, handling, luxurious leather interior, ventilated seats (these are awesome on hot days!).
I find the gas mileage rather average. I would also tip the lights up a degree or two - at night, the projected distance of the regular lights is a bit short. While I don't think they are dangerously so, a couple extra degrees up would help.