Purchased my 450H about 3 weeks ago. Drove ML320 for 200K and fully expected to get another one, but after test driving the 450H I was sold on the ergonomics, fit and finish, and the gas mileage (twice that of my ML). Navigation system, design and ease of use, comfortable, quiet. I loved my Mercedes and it was a great car; but the mileage, design and comfort of the Lexus won me over. Would not change a thing, except maybe the price. But, compared to similarly equipped cars of this quality, was not too painful. BTW, don't seem to lose a thing in the acceleration. Handling and cornering a little soft, but you still get a sense of the road. Lot of great little features I haven't even tried yet.
Navigation system, blue tooth, mouse like access to systems.