I own one, in fact I ordered it specially. I'm not adverse to nearly new, but try finding the petrol CGI's.
I will list the negatives, most of which are general E class negatives:
Gearbox easily confused - seamless changes, just far to many of them!
Not wonderful at demisting.
Command is rubbish, don't pay a premium.
CGi very noisy on cold tick over, silent when warm.
Car is very wide, but easy to place. Doesn't fit any parking spaces (except Costco).
Tinted windows in this weather is very grim inside for passengers (so I never ordered!)
Steering feel awfull/rubbish/disconnected.
Load liner fouls the United-slammable electric tailgate half the time.
Factory rear mats dont fit the longer wheelbase wagon.
Positives:
Extremely comfortable.
Very sweet sounding under hard acceleration.
Incredibly quick.
Boot is huge.... (But not deep enough - you only get 5 foot diagonally)
Not everywhere like C class.
Three adults can comfortably travel long distance in the back without being crippled.
Economy:
You might drive like mother Theresa on Valium. Sadly I don't, I try to it just never happens! Let's call my style "making progress"
I get 26.9 MPG (average over 5000 miles) of which 4000 miles stop start A/B roads, 1000 miles motorway, cruise on 80mph.