Having just driven a 190D 2.5, I can say that the fit and finish is there...but you are reminded constantly that you are driving a smaller car.
The RPMs at highway speed are kind of high (3000k at 65-70)...at least they were in the '86 I was trying out. The benefit, though, is the 35ish MPGs I was getting. Very M-B, but a "junior" M-B. Engine is basically bullet-proof, but it seems that the W201 series suffers from "3rd owner syndrome". Everything is neglected and you get to pay for it. The good side is that most everything except for engine components are interchangable and even the rear diff can be changed out to lower those revs.
I will still probably buy the '86 I was looking at.