4.5 stars (if I could) as the flavor palette for several dishes overlapped a bit too often, and the price (250 CAD) is the highest for any tasting menu in Montreal, while not being the best restaurant in Montreal (Bouillon Bilk would get my vote there). That being said, Le Mousso is still a treat and an experience, and a really solid fine dining option for Quebec at large. What I liked the most:
1) In 138 Michelin restaurants, I have never ever been to one in which the chef and the sommelier will come out and make a speech in front of all diners about every single dish and drink you are served. I loved the theatricality of this!
2) Some of the dishes are completely eye-gasmic.
3) Even more importantly, several dishes are completely taste-gasmic! The onion cream caviar dish was one of the most delicious dishes I have ever had anywhere. The lobster taco, the cotton candy foie gras on a stick, and the 1st dessert (I forgot the name though the milk cream/custard was infused with a smoky-ness that was amazing, especially for a dessert!), were also exceptional.
What I liked the least:
1) We arrived on time for our reservation, and the first course did not get served until nearly 1 hour later. The reason for this is the meal couldn't start until all diners were present in the restaurant, as diners are all served each course simultaneously. Not only did this delay the start, but throughout the meal, we would wait and wait for slower diners to finish their courses. When some diners are seemingly more interested in conversing than eating, that especially becomes a bit annoying.
2) As mentioned earlier, some of the flavor palettes across dishes were too similar. Both of the desserts were similar white cream/custards (one milk focused, one corn focused), and I would have liked to try something different for the 2nd dessert (something fruity, or chocolate-y). Several of the mains also had the same savory bourguignon sauce/taste, and I'm not sure why each dish wasn't more unique.
3) Each dish that just had one stand alone item (a piece of meat, a piece of fish, duck) was lacking. Clearly, the chef's intent is for you to focus on that item (since there are no sides), but when that item doesn't blow you away, you end up eating one block of meat or fish that isn't that special, and wish there was more creativity and ingredients in the dish.
Overall, this still gets 4.5 stars from me, and I don't regret eating here at all, I just wish Le Mousso did a few things differently to go over the top.