Looked an the usual suspects - E550, 550, A6 V8. All nice cars, but none of them had the balance of exterior design, interior style, performance and value. The 2011 MB has no style, BMW is way overrated and need to learn how to do an interior and the Audi needs to be updated. Just look up the performance numbers - the Infiniti has a great ride and is luxurious.
I'm happy with just about everything on and in the car except the transmission is jerky and undecided as to what gear it should be in at slow speeds. Between 20 - 40 mph, the gears shift up and down over 1K rpm because the computer can't figure out what gear to be in. The car actually jerks back and forth. Infiniti knows about this and is working on it.
Infiniti has gone to great lengths refining many aspects of the M for 2011 but there are still many things that need improvement. While I enjoy my M56 a lot, there are features that worked better on my '08 M45 (such as XM NavTraffic, which is a disaster on the M56 and every other 2010+ Infiniti model). And there are features that are completely backwards, like the armrest button you press OUT to fold the side mirrors IN, and the song selection button you press UP to switch to the next song DOWN on the list. Doors lock automatically at 15mph and you can't do anything about it. And there is so little ability to customize the warning/intervention systems that one is inclined to leave them off!
The only thing better than my M45, was the M45X I purchased, then along came the M56X - I got one of the first in the region. Nissan really listened when they built this. Everything has improved, and the additional horsepower puts it into a different league. I love the ride - feels more substantial, and corners like it's on rails with breathtaking acceleration. My wife says it reminds her of our BMW 750 - but more fun, with a sexier interior and exterior. Electronics, back up cam, sound system, etc. all exceptional. They even added a heated steering wheel and retractable outside mirrors. The dial-a-transmission is very clever. Bravo!
I have been driving BMW 550i since 2006 (first release of 550i). I cant deny I had a lot of fun and appreciation toward my Beemer. But I did not notice any subtaintial improvement from the model 2006 to 2008, even the HP remained the same between 2006-2008, this year they did man up to 400 HP...but the price also jump to almost 1.5 times. So I took a look at Audi, Lexus, Acura and eventually ended showing up in infiniti showroom. I was not really thrilled about exterior but the performance of the car is outstanding. The comfort seating, smooth driving and the 420 hp did blow me away. The navigation system, rear view camera, and the gear mode changing are excellent...