Smoooth best describes the GS 300 AWD. Have owned a number of mid-sized sedans including BMW 5 series, and Audi A6 2.7t, the Lexus is considerably quieter with a smoother ride, but gives up a bit of ultimate handling if you like to shave a 10th of a second off your time turning into the local shopping center. On the highway, it's hard to beat with a natural (and potentially ticket collecting) cruising speed of 75 to 80 mph while returning 26 mpg. Overall, if you are not driving at 10/10ths all the time, it's a great compromise between ride and handling, not to mention Lexus reliability and build quality.
The Mark Levinson sound system is in a class of it's own... it's subtle, but the more you listen, the better it sounds. The AM & FM tuner are superb. Also love the the keyless entry and start button... it's a "must have". The HID headlights that "steer" are great.
The nav & phone only allow you to access pre-programmed locations and numbers while moving. Otherwise you must stop, although you can cheat the phone by dialing from your cell, but the connection takes much longer. Overall, a little too much "Big Brother" for my taste, but nothing is perfect.