It was tough to let go of my '99 E430, but the 2007 E550 Sport made me forget in less than 6 seconds, zero to 60. The car is a perfect blend of luxury and power. I was close to buying the BMW 550 but the new E class facelift, Sport Package,(if you consider close to $70K free) 384 horses and add-on 18" AMG 5 spoke wheels with staggered Michelin Pilot Sport tires changed my mind. Time will tell in terms of reliability but I had good luck with the 99 E430 and I expect the same here. I am pleased so far with the 25MPG on the highway. The trunk is deep, not wide. Not easy to sling one golf bag, let alone two, in the trunk. I'll deal with it. The electronic trunk closer makes it worthwhile.
Adjustable suspension (sport v. comfort), heated and ventillated (not AC) seats, wood/leather steering wheel and the 18" AMG wheels. The car is definitely a looker and if you don't like who's looking, you can leave them in your dust. The NAV is intuitive, but the system in the trunk takes up width.
The speedometer cluster lighting on the Sport Package does not match the rest of the instrument lighting. The "cornering" foglights are not near the experience of the BMW "cornering" headlights. One has to "mute" audio when NAV is operational instead of turning audio "off" while keeping NAV "on".