I test drove the non convertible version of that when it first came out, and i didn't like it too much. It was VERY cramped, esp when you got someone in the back (not a likely situation, but still...). I do admit that there are some cool technological innovations, such as the iDrive system and the one button control for everything.
The computer did not seem very logical to use though. Overall, the car was overpriced for what you get. I would much rather drop my 90g's on an ///M or a 7, or even...dare I say it? A mercedes
I absolutely love driving my dads 04 SL55 AMG. No BMW can touch that car... You can buy a nice used Sl500 or 55 for the relatively same price range as a fully loaded 6, close to 100g's.
Just my opinion, don't know if anyone agrees