I got one and we love it, we are a large family so the 7 seat is essential for us well we ar 6 people, so we use the 7th seat for luggage and we look for roof box be course there are no room for anything when you use the seats, thats about the only issue i think there is, but its kind of obviouas when you look at the car so we knew we had it coming.
Well okay, the heavy drinking, could be considered a problem to, it is the heavy'est drinking diesel transportation device is you look away from 18 wheel trucks ;-), but we work with Bluespark Automotive on the Scandinavian market and we kind of tok it as a challenge, it was doing 36-38 MPG before, now we have an total average at 23 MPG regardless almost what we challenge it to do, next test is fat offroad tires and a Roof box for max resistance :-)
We haven't had any problem yet, but i suspect that the automatic gearbox are the only week link, people tend to be fooled by the fact that its a Mercedes diesel that are known to be callable of 1 million miles or more without problems, just regular service, but the gearbox are NOT from Mercedes neither are the rest of the drivetrain, so if the engine goes like a million miles i will suspect that you change gearbox 3 times :-)
Just bare that in mind and you will have a blast in a car like that, we really love this car, and i really can't tel you what exactly makes us do just that, be course its everything we are not looking for in a car, we just needed the 7 seat option. normally cars last about a year here at our house, this have been with us for 1,5 years and absolutely no plans to sell it any time soon, just ordered roof box to salve the luggage, might have been easier to go for a Surburban, but thats not a Commander is it ?