I bought this car used, with extra low milage, from an owner in Italy. Although I was never a MB nut, I can see why people love the brand. It is, for a 13 year old car, a step above most cars that are supposedly younger, better etc. and cost the same if not more. While reliability is an issue in the W210's, you can't expect a 13 year old car to be flawless or not experience any mechanical failures from wear and tear. From my research, the W210's are the last of the proper German engineered and assembled MB's (some say the W124's were the last such breed). If you are planning on buying a used W210, especially the E420, take it to an honest MB dealer and get it thoroughly checked. Then enjoy.
The comfort. The big V8. The rumble of the M119 engine. Silly creature comforts that most American brands are offering now as "new" innovations. The W210 at introduction introduced a completely new styling paradigm that still feels "different" and has been copied by many a car company to this day.
If you are buying a used one, service history is key. Make sure the car has been taken care of. Check for leaks, check the transmission, all the most common things that go wrong (just google it). Be warned, if you can't do some mechanical things on your own, the MB dealer is quite pricey.