After dining here multiple times, I can confidently say that this restaurant is only good for the gimmick of eating in the dark.
The service is great and usually timed very well to allow you to have enough time to chat with your date or friend without letting you go hungry. You must also keep in mind that the style of service is very different from typical restaurants. The servers will not be checking up if you need more water because they can't even see if you're finished! It is a bit ridiculous to expect this restaurant to have the same service as a lit one. The servers are very responsive so call out to them if you need anything.
The food is average at best. The experience of O.Noir is supposed to "enhance your other senses", but if your food is overcooked or too cold, having "enhanced senses" are not going to help you overlook this.
Make sure to wash your hands before you eat. You will most likely be relying on them to eat your meal and to check if there's anything left on your plate.
It's nice to try this place once. Other than that, you can find better food elsewhere for a better price.