Our stay in Sigrid loft was lovely. The house, clean and tidy, is one big environment (a small loft) with no interior walls. Everything (even the shower!) is integrated in a big closet. At first is a bit weird but I must say that everything works well once you get used to it (even the shower in the closet). I've read some other reviews saying that the house is cold, but it's not the case. It's just that the heating system is in the floor, so it needs a bit of time to kick in, but once it does the house is very warm.
The toilet is right next to the bed, hidden behind a movable wall. It's is not the most private bathroom I've seen, but if you are not so shy (or if traveling with someone you know) it shouldn't be a big problem... at least it wasn't for us.
There are no thick curtains, so at sunrise a lot of light will come in. Sigrid gave us free eye covers. Because we stayed in winter, when the sun rises very late, we didn't need them, but in summer you may need to use them.
The apartment is 15min walk from the city center, 1 min walk from metro stop (line 51) and 15 min walk from Brussels North train station (which is great to visit nearby cities like Bruges).
Overall a very nice place to stay in Brussels