AOK.
The US terminal sucks quite frankly, while the main terminal ain't half bad. US flight leave out of the "closed down mall" and dining options are terrible. Greasy yucky Tim Hortons or greasy yucky Burger King. Long awkward terminal, bathrooms are coed one offs. Fabulous..if you like cleaning bathrooms before you "go"......really not a modern, pleasant or efficient terminal. Security and immigration lines can be super easy or super long. You never know- I always get there about 1.5 hours ahead of flight.
There is tons of duty-free- all the maple syrup and ice wine one can carry.
As to the main terminal, not flying to the US:
The terminal was quite easy to get checked in and through passport control. We waited in the Chinook lounge which had a spectacular view of Calgary against a backdrop of the Canadian Rockies. The lounge had wonderful sandwiches and snacks, and a full spread of beers and beverages. I had a coors light for Denver mixed with Clamato for Calgary.
Found a great popcorn shop just before my flight!
Appears to have plenty of shopping, but only a few sit down restaurants and not a lot of healthy options. Also, I looked, but did not find a Duty Free store.