Personal Opinion: ALL Mercedes cars have a TERRIBLE looking interior!!!
By the way, this is a relative comparison between high end cars and not low/average... (I'm not comparing the M-B with a Chevi for example...)
When rating the interior, one must look at several factors: Design, simplicity and accessibility, high features (despite having simple design), luxury & comfort, beauty and harmony in compliance to the exterior.
I'd say among all these, M-B might have a chance at the comfort (and partly luxury).
I found the cockpit very complicated and unharmonised, too many buttons and sophisticated for a new design (remember, high features doesn't mean sophistication!)
then again that's a personal opinion and for others it may be different...
Beauty is absolutely not there...
Even in other models on M-B, I find the exterior nice (CL, SL and SLS have better extriors than the rest) but then once you see the interior....