I am a current owner of a 2001 C240.
Yes, my door does the same rattling sound when it shut, as also described by Larry. Also, there are a few intermittent squeaks and rattles in the interior. It's nothing major, but it's just annoying sometimes.
Otherwise, it is a great car. The steering is very accurate and the handling is very neutral. Also, as expected, the car does have the typical Mercedes "glue to the road" sensation when traveling at high speeds. Wind noise is almost absent at speed up to 120 km/h. The car is quiet, as road and tyre noise is minimal.
Because of the weight of the car, don't expect the 168hp 2.6l engine to pull very briskly from standstill. But I have no complaint about the power, since I am not crazy about how fast can the car goes from 0-60mph. The power of the engine is more than adequate for me. Furthermore, my car comes equipped with the 5 speed automatic transmission. The transmission shifts smoothly, as expected from a Mercedes.
If you think the C240 is for you, I suggest that you take a closer look at it. It is more expensive than a BMW 325i and an Audi A4, but in my opinion, the C240 is a better car overall. Furthermore, nothing beats the prestige of the three pointed star.