I have owned a '99 ML320 since new and it now has 105,000 miles on it. I love the ride and utility of the vehicle and to be fair it has never failed to start nor has it ever stranded me except when the battery failed (and then a nice MB tech arrived to replace it at cost of battery). That said, the quality stinks. The car has been in the shop about 20 times for various bits and pieces failing or falling off. Everything from rusting lug nuts (within 90 days of new) to a failed steering sensor (requires replacement of entire steering column). This car is expensive and annoying to keep on the road. Final insult is that now the driver's door has penetrating rust. Buy a Honda Pilot instead.
Quality of components. I have replaced instrument panel, fuel tank, various engine sensors, radio/CD, power window switch (same one twice), fuel gauge, cupholders, multiple trim pieces and other electronic gremlins. No excuse for such lousy unMB-like components.