Purchased ours used in 2011.
Since (Just over 4 years) then we have spent roughly $9,000 in repairs (not maintenance). That cost does not include the warrantied timing chain, catalytic converter, numerous recalls and other warranty repairs. It also does not include the free parts that GM Canada offered because of the repeated problems.
The Acadia has 3 catalytic converters, they have all been replaced at 125K and that was after one was replaced under the warranty at 90K.
We have replaced every plug coil (130K), the timing chain (90K), repaired a leak caused by a defective moonroof drain tube, the entire power steering system (150K)
The only reason my score isn't an absolute zero, is that it is a comfortable vehicle and quiet practical since we have 3 kids who all play competitive sports.
Customer service has also been a battle, had to take matters to CAMVAP at one time and was awarded a refund on repairs. Those repairs are not in the total either.

Do your research and have it inspected by a third party before you buy.