I recently traded my 2009 Acadia SLT2 with over 120,000 miles for a new 2012 Denali.
I only traded the '09 because of the number of miles and the attractive trade deal available.
I loved the old one and like the new one even better.
The mileage has averaged in the 18-19 mpg range overall.
I have hauled as much as 1,000 lbs and only felt a small amount of rear sway.
My only real complaint is that front headlights can only be accessec through the front wheel wells.
This is the best all around vehicle I have owned!