This. Place. Rocks. If it's available, book it now.
Now, a brief comment on the bulk of the "dirt" on Tarik's places in this building - yes, it is loud. You are in the heart, the HEART of Brussels. You're on a busy cobblestone street, with a plethora of restaurants, bars, and people enjoying their city. You will hear people and street noise, bring earplugs. Problem solved!
Now that we're out of the way of the nonsense bad reviews, this place is awesome. This is my 3rd trip to Brussels, and I'm never booking or looking for another place to stay. The location, for the price, is unbeatable.
Check in is breeze, and it's convenient. Sure, there's stairs and no elevator - welcome to Europe. Your place will be clean, smell great, and be comfy. Sure, it's minimal but for a solo traveler I found it perfect. Bed, comfy. There's a small table with 2 chairs, and a decent bathroom. I would say this would be comfy for 2 travelers as well. Like I said, you can't beat the location. You can spend all day out, or take breaks in between your day because the location of this is so central it's ridiculous. I also loved the blackout curtains, let me sleep in a bit :)