If you're used to Chinese restaurants then it's fantastic, but otherwise the atmosphere can be quite loud and messy (especially the washroom!) and service would be considered bad. We arrived later around 9PM and it was only starting to pick up. Apparently they open until 1AM.
We were visiting Calgary and came to Sun's in place of Tai Pan and we were happy to have done so as the food was beyond our expectations. We all agreed that this place might have been the best meal we've had during our entire trip. We were seated quickly and food arrived fairly quickly. We were sitting closer to the kitchen so we never had a problem with our tea being left without a refill. The service was meehhh but not terrible. And my Aunt and Mom spoke Canto so that may have helped. Pricing was decent. They charge for rice but each bowl is massive and can be shared between two people. If you enjoy the smokey-wok flavour type of Asian food (and on the saltier side) then this is the place for you.
Food has to be exceptional if service is meehhh!