Not only fun and unique, but food is delicious.
This could be considered one of those experiences you have to try once in your life, but I've actually been to this place 3 times in the past year. Coming with different people always makes for an original dinner.
Menu is seasonal and changes slightly, so make sure you check their website ahead of time to know what you will order. If you're feeling very adventurous, you can opt for the "surprise" dishes. It will only be revealed after you're done eating. You can choose either a 2 course or 3 course meal.
I've had their avocado salad, filet mignon and creme brulee for dessert which was always superb. I like that your meat is already cut up for you. You will be provided with only a fork and spoon. No need to worry about conventions, it's perfectly okay to even eat with your hands as you may have a hard time figuring out where your food is on your plate!
Lots of laughter guaranteed. This place gets very loud.
If you need to go to the washroom, call for your waiter by name and he/she will guide you. There is dim lighting in the bathroom.
I highly recommend this concept of eating in the dark, it's gaining in popularity around the world and there's actually another Montreal restaurant with a copy cat name - although Onoir was here first ;)