Would I come back? No.
This is another gimmicky Markham dessert stop. It's a cute one-time experience, but it's really rough around the edges, from the service to the interior layout to the cleanliness.
There really isn't any flavour to write home about. The ice cream was average at best. The syringe, frankly, has nothing to do with anything and is essentially a gift to the landfill. Even in the sense of a gimmick and the liquid nitrogen shtick, it has no place.
I think most concerning was the way they pour the liquid nitrogen kind of haphazardly on the ice cream on the counter where people are often waiting for their orders. It's flying and falling off the counter, right onto people standing there. It just made me uncomfortable, particularly when there were kids nearby.
Do it once if you're curious, but you'll realize soon enough that it's a one-time gimmick. Unlike Woofles & Cream, which was also once the newest dessert craze in Markham, Cool N2 doesn't actually have a good product. They have a mediocre experience and a mediocre product.