What are those "horror" stories you have heard about the "E" class?

The breaking rear window regulator (a do-it-yourselfer) costs about $200.00, the disintegrating harmonic balancer is covered by Benz (there is a long thread on this site, in any case you can check the serial number on the part itself and see if it had been changed or not) and the spring perch problem may only be an issue if you purchase a car from the snowbelt area. The transmission meltdown may or may occur at 100k miles, make sure the car had the t.oil/filter changed and you should be OK.
I have an MY 2000 E320 with 50K miles on it and not a single issue so far (I just replaced the battery last week as it was original and started to loose charge). I also changed the tranny oil/filter last summer just in case (and the thermostat as it was sticking). The outgoing oil was the same color as the oil that went it. Cheap insurance anyway. Other than that the car had been trouble free. What I don't like about the 210 is the turning radius, the damn thing turns like a tank compared to the 124, and the soft suspension (however my old 124 was lowered). Other than that it has been a wonderful car so far.
I can't speak for the older years. There was a face lift in MY2000, the new ones look better and have a few more features.

Alex