My friend and I both bought SLK's in 98 and had similar experiences with reliability issues.The top sometimes jams in a partially open/closed condition, tail lights have a propensity to melt, and the interior side panels were replaced twice under warranty due to separtation of the vinyl from the cardboard backing. Otherwise, the car is a blast to drive and really handles like a sports car. The seats initially feel like boards, but after a few minutes, they actually fell quite comfortable. Lots of power, and reasonable fule mileage, though it requires premium.
The retractable hard top (when it doesn't jam) and the handling. Decent trunk space, even with the top down.
Mercedes needs to give a customer more quality and value when you are spending over $40k for a car. Marginal radio, no CD, and a not so small number of repairs at Mercedes repair prices.