Simply one of the best BnBs I have been to! It is located at the heart of the city center, perhaps just 2 - 3 minutes away from Grand Place. Although it is conveniently situated at the center of Brussels, we did not hear any noise from the raucous streets of the city at night.
The place was sparkling clean and had all the amenities that anyone would need for a comfortable stay. In addition, Bart, the host, was very clear and prompt when I asked him questions about the apartment and Brussels in general.
if I had to nitpick, I would say that the apartment is perfect for 2 people. There were 3 of us when we stayed (i.e. my parents and I) and the space was fine for the most part but I imagine that this cozy apartment would work best for 2 people.
All in all, I highly recommend Bart's apartment! This should be an automatic booking if you are going to be in Brussels for a few days!