It started leaking oil 10 months after I bought it. I was in Germany at the time but fortunately had a German speaker with me and so I was able to get it fixed under warranty, although we had to visit 3 dealerships to do so!
The car is a bit under powered but very comfortable. I have had experience of two dealers both of which have been totally incompetent which is why I'm unsure if I would buy another Mercedes.
Agreed they can tend to look down at you or ignore you if you don't wear a tie and some kind of smart dress. I wouldn't mind, but look beneath their uniform and they're a bit of a common lot too in some cases!