Back about a year before the ML320 was available, we decided to plunk down $1000 to reserve one. This was a new kind of experience for us as we'd never owned a Mercedes before, nor had we ever waited an entire year for a new car. On balance, I'd have to say that I'm glad we did it, and that the car has worked out well. However, there are a few points I'd like to make that seem inconsistent with the mystique of a Mercedes.
From a comfort and performance perspective, the ML320 is a winner. The seats hold you nicely, the heated front seats are great in the winter, and the off-the-line performance is more than adequate for what really is a truck.
Where the ML320 falls down is in the details. The car has more shakes, rattles, and rolls than a dance hall. The fit and finish is borderline unacceptable. The paint is almost amateurish, and the quality of the service (oil change type stuff) from the dealer is nothing short of disappointing. The first oil change we got had the o-ring pinched when the filter was replaced, causing a leak that soiled our garage, and forced me to return to have it fixed (you need a special tool to remove the filter of course).
Given that this was the first model year, I'm going to give Mercedes the benefit of the doubt, and assume that the car is put together a bit more competantly in later model years. If so, overall, this SUV is as much fun as any other car that I've ever driven, and I'd highly recommend it.