Six months ago I traded in my beloved '03 Escalade for an '06 R350. It's a keeper! It has more interior space. Performance? The 268hp v6 lacks take off, but will shoot you to high speed with surprising ease. It corners exceptionally well also. Comfort? It really will fit six 6' footers comfortably (did that) or the wife and 2 kids with plenty room for groceries. Fuel economy? In the city it's about average (if you have a heavy foot), however, highway mileage is excellent. We (3 adults, 2 kids, and travel bags) drove from NY to NC on a full tank (500mi). We cruised at 80mph.
Sport/comfort dampening controls, panoramic roof, interior space, reliability: I bought it used (43,000mi), took it to a Benz dealership for an 'A' service even though it was only scheduled for a 'B', and 12,000mi later. No problems!
Opting for the 303hp v8 of the R500 would probably curb my yearn for more horses, maybe. But with limited rear and rear/sides views, Parktronic should be standard on any R Class. Fog lights should be, too, with HID options.