Gavin,
I've driven both and there are a number of things I liked about the Acadia better, mostly handling and looks. Some of the interior on the Acadia seemed a little cheap though. I would look into the cost difference between the Acadia and the Buick Enclave if really interested, or the Saturn Outlook for that matter...pretty much all the same vehicle. They all differ in styling a wee bit (sorry, sat next to 4 Irishmen on the plane back from London).
TJR