Well, it's a mercs, so luxury is definitely associated with it. But what impresses me, is how clever electronics are well built into the car.
The 2.6 v6 delivers power easily and gracefully. The gentle yet audible increase in engine roar as you apply wide open throttle, impresses you with its willingness to deliver.
Handling is pretty smooth, and ensures a comfortable ride. It is afterall, a luxury car. However, in comparison to a 520, I believe it lacks the BMW's finesse and sharpness. The chassis is perhaps, not as sorted out for performance.
I like the nice digital speedo, which allow driver to switch from mph to kmh(not much use, but still nice :p) . My favourite part of the car, is playing around with the cruise control. Once it is activated, you'll see the speed reading on your speedo. It's a real kick, to have your leg off the accelerator, and flick the lever on the cruise control, to accelerate, or decelerate. It's almost like playing a racing simulator on your ps2 haha ;)