It's a Mercedes. What's not to like? Love the side/rear views. I don't love the front, but the S-class interior, amazing sunroof, power everything, and extremely pliable ride quality more than outweigh the taffy-pull minivan front end. The V8 is strong and the 7- speed transmission is so smooth you can't feel the upshifts. Occasionally you feel a downshift if making a "rolling stop" but I learned that sometimes this phenomenon is due to hill start assist applying the break when you're rolling a stop sign if on a hill. Interesting...user error, not clunky transmission.
Glass full-panel roof. Seating with back center console makes it "sedan- like", ride quality that isn't jarring like an SUV. Powerful engine / transmission. Upgrade HK stereo a must. Auto-blink turn signals upon touching turn stalk (you'll miss it in the rental).
Touch screen nav and better graphics. Standard xenons, LED tail lights like the rest of MB lineup. Better looking wheels on all R-classes (R500 standards are best option to avoid minivan look). Choice of Sirius or XM. Standard parktronic or rearview camera in such a vehicle class.