Perhaps a great deal. Did you look at any new 09s which presumably have some manufacturer incentives such as 0% or cash back? While yours has no miles, it is going on two years old. Enjoy the vehicle - Im certain you will.
Congrats on your purchase, and welcome to the forum. As JSIMMS has asked, please update your profile and signature with location and specifics about your new Acadia, this will help reduce repeat questions about your vehicle when you strike up a conversation.
I pasted some Edmunds True Market Value reports of an 08 Acadia FWD with 535 miles. One report is LOADED, the other is basics. Hope yours falls in the bracket accordingly.