This is a fantastic find for staying in Brussels. Its well equipped, nicely decorated, spacious, bright and well located. The only downside is that the bedrooms are facing a pretty lively street where people were hanging out very late on both nights I was there. Some people might manage that fine but as a light sleeper I struggled a bit. The upside of that is is you have a good pick of restaurants and bars nearby.
I stayed two nights but it would be a comfortable space even for a longer stay. As others mentioned, its up two flights of narrow stairs, one of which is steep, so worth bearing in mind if you have mobility issues or travel with big suitcases.