I think they are pretty much the definition of middle of the road reliability. They price accordingly though and offer a 6 year 72,000 mile warranty, which ain't half bad...
We've had one for about 4 months now and have 5500 miles on it. It's been on two road trips. We really like it. My only complaint is the gas tank is a bit undersized for a vehicle this large, so road trip stops occur a little more frequently than I'd like, but not a huge deal.
Overall, it's WAY better than our 2012 Acadia we traded in for it.