We currently have a 2009 Mercedes Wagon with 15k miles on it. Also for context we have a Toyota mini-van and a Prius. This current wagon only seems special when you are on the highway. There it is in it's element. Extremely smooth, quiet yet with the classic German feel. Other than price it isn't much different from the Toyotas. Overall build quality actually seems to be less than the Toyotas I am sad to say. We have had a number of minor problems with the electrical and mechanical systems. The CD player still doesn't work. The right windshield wiper stopped working etc. In general it seems as the though the car is several years behind the competitors in features.
Having always owned BMW's (since the 60's) and learning how to maintain and fix them, I've enjoyed German quality and engineering. However, of late, they have become so sophisticated, I no longer have the ability to do any work on my cars, which I enjoy doing. My wife had always wanted a Mercedes wagon and we found a very low mileage single owner 2009 E350 4Matic wagon and bought it. We mostly use it for trips and enjoy its comfort on the highway. Although it isn't fuel efficient, it does perform well. From the first day, we have been unable to figure out how the Navigation system works (glad to have Waze on our smartphones). The sound system is equally challenging to operate. The trip info on the dashboard is hard to read and understand when driving (too much info). Our fan motor has a squeaky bearing ($450 to replace). At 65,000 miles we have learned the rear differential needs replacement ($3,500). Compared to my BMW's, I am disappointed with this car. The local dealer is sells "units", not cars. For someone who has been a lifelong car enthusiast, I'm not fond of the dealer or the brand.
I have always wanted a MB wagon. I have not been disappointed. Solid and reliable, quality constructed both inside and out. Great handling for a wagon. Only service has been 1 year standard service. The nav system could be easier to use, but ut us on the mark.