I would give this Cafe between 3 to 4 stars in general. 4 because of the space. Although tiny, Leaves Cafe really maximizes it's space with small tables, bar seating along the side, and a beautifully minimal aesthetic. There is ample natural lighting and some exterior seating on the sidewalk. It is a great place to sit down and read a book on a lazy afternoon in downtown Montreal.
I would give it 2-3 stars for the coffee/food. This is a coffee store with a healthy range of drinks however they don't have any milk or dairy products because they aim to be cruelty free. While I don't mind being "low impact", I really do prefer my coffees, lattes etc with milk or cream in them. You have a choice of almond milk, coconut milk or soy milk. I was recommended the coconut milk as being closest to the real deal. They do take their time to give you a strong cup of joe by making it as a pour over, however I found the coffee to be quite acidic, possibly because there was no milk in it or maybe that was just the kind of bean they had.
Tip: there is wifi but I couldn't get it to work on my devices.
Overall, while I love the space, I can't quite get behind non-dairy coffee based drinks so I might return for a baked good or two but not for the coffee.