 Just bought the E550 4matic a week ago.  Love the car.  It came down to the audi A6 or 5 -series.  This car is much better in both build and drive. The V8 is very fast and smooth.  The HK sound is awesome.  The Xenon lights are great! Once you use them, you won't like regular lights again.  The only things I haven't liked is the COMMAND function.  It's ok to use.  More complicated than it needs to be.  The IPOD interface could be better.  I got the sport edition.  Not much difference in ride quality between sport and comfort modes.  The car height feature is pretty cool when parking near a curb.  It raises the car about an inch so you don't hit some concrete curb when you park.