The R350 was a very good choice at the time of purchase because it was the first true cross-over that focused on room & comfort. The interior design is ingeniously ergonomic. The performance is quaite acceptable for a station- wagon type vehicle. Much to my surprise, there were quite a few intermittent reliability issues (i.e.; the rear hatch would drain the battery in wet conditions. MB did not figure this out until the hatch completely failed.
Drives well in almost all weather conditions. Very comfortable for all passengers on long trips.
To meet the MB expectation, I think better thought should have gone into how the systems interact. A faulty hatch or feature should not result in a dead battery that leaves you stuck.