I went for lunch with a group of co-workers and the food and cocktails were fantastic! I had their burger and it was one of the best I've had in Montreal. The bun, toppings, sauce, and beef were amazing. Their fries are crispy, perfectly salted, and seem almost addictive.
The only issue was the service. The server forgot to bring an item for one of our party, and only brought out 1 small mayonnaise and 1 small ketchup even though 4 of us ordered fries. The waitstaff were nearly impossible to flag down - we tried to talk to them and even waved our arms as they walked by but they seemed obvious (and the restaurant was only half full). I suspect the poor service was due to the fact that the restaurant is so new and hopefully they'll improve after a few weeks.
I also want to note that the restaurant is beautifully designed. It feels very trendy but welcoming.
With a small tweak to the service standards, I think Foisgwa will do spectacularly well. I can see it quickly becoming a favorite lunch/dinner destination for me.