I think this is a case by case situation. Some cars will have more problems than others. I am sure that was the same as on the W124.
Each model has its "common" problems. W124 has the headgasket and bad wiring harness problems. W210 has some rust problems.
My 96 W210 has the same M104 engine as the 97 and its been a solid perormer. I don't have any rust problems. Someone mentioned HVAC and electrical problems on this model but I don't think those are common problems. Some of the latter years 98-2002 have the Harmonic Balancer problems.

Take the car to a Mercedes mechanic and get it checked out before you buy.
Thats the best advice anyone can give you.

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2010 W212 E350 Sport
1996 W210 E320 (220K miles)