I have an '06 C230, the baby sister to the baby benz
I lurve my car with everything in me.
I love the drive, the handling, the classiness of it BUT the only thing I have found is that my car stays in the shop for little stuff. When I was doing my research to buy (choosing between it, BMW and the Audi A4), many of my friends who owned warned me that I would experience problems with it.
So far nothing major and everything is covered under warranty. I did cough up the extra dough for the Mercedes Benz care plan though, because of their advice.
When I say little things I mean stuff like: I've replaced the motor in my sunroof 2 times already, there was a squeaky "spring" or some such that made the car sound like it was about to fall apart, they said it was a known defect and fixed it, the aluminum around the lip of the cup holder started to peel within 6 mos and they replaced it, etc...just annoyances.
I did not purchase the extended warranty since I only plan to keep my car for one more year, but if you plan to pay it off and keep it, then you might want to invest in that.
Other cool stuff:
The car brakes around corners for you, lol. Seriously if you're going too fast it gently applies the brakes to keep it on the road. In the 240 I am pretty sure that it has the rollover sensor that closes the open windows/sunroof if it senses an impending rollover.
I am a Mercedes fan for life!