Simply the best. This has been my go-to Indian restaurant since I moved to Montreal. The staff is so friendly and helpful, and the food is just insanely good for the price. My normal order is a non-vegetarian Thali and a mango lassi, and I've really never gotten anything bad on my plate. The butter chicken is good, but my personal favorite would be the beef curry.
I've also had a great experience with the fried snacks they offer- chicken pakoras are the best I've ever tasted, and I love their samosas, alu bonda and bhajis too. Delicious barfi ($1 each and worth ten times as much in my opinion) and kulfi for dessert.
If I had one complaint, it would be that the dining room is very very crowded and busy- the result of their amazing food and service. As such, I normally take my order to go. Cannot recommend Thali highly enough.