Bought an LS 430 after seven years of Mercedes-Benz. Knew to expect silent operation, but was still surprised by the power and quiet. It's like being pushed by a huge electric motor. No vibration, very little sound from the engine, and tons of torque. The LS 430 is also surprisingly agile and, like other great luxury sedans, it seems to get smaller and lighter as the speed increases. I took an interstate cloverleaf at 60 mph with no tire squeal and complete control. Everything about this car is supremely well-engineered and manufactured. One nice feature is the auto-level on the xenon headlights so that they never blind oncoming drivers. Very thoughtful. Really love this car.
Big interior (I'm 6'3"); quality of everything from soft leather to just-the-right-amount-of-friction knobs to ergonomics; climate control can freeze, bake and everthing in between; trunk is huge; overall gas mileage 22 mpg at 290 hp/320 fpt; can adjust front passenger seat from driver's seat.
Give it a little sportier handling, but only if it means no loss of supremely quiet ride; give it a long-wheelbase option; it still looks and feels like a big, luxurious Toyota, which it is for better or worse.