Interestingly enough, it doesn't seem dated at all in person. The lights are extremely 'futuristic' and the technology is astounding. The older model was quite sleek, and very classic SL, but the tech wasn't there, both inside and out. The 6-speed was clunky and slow if you didn't allow the car to do its thing and even though it was a naturally aspirated V8, it redlined at about the same RPM as this model. And the speed and handling difference is really something when you drive both back to back.
I will admit the wheels look odd from afar, but they look great close up. Same with the styling. But that's my opinion.
There are some things I miss from the old car, but I would say that this model is a complete improvement.
On another note, I don't think I would have this car over my 335is. I love the exhaust and handling feel of my car and really do believe that the SL is a true grand tourer for an older person. It's quite refined, but steering is very electronic as I stated and the transmission is still a bit slow. Definitely a 'passenger's car'
(Now the SL 63/65 ... That's a different story!)