We had an amazing time in the apartment. It's quite compact, but has everything you need for a short stay in Brussels. It's very bright, airy and right beside the main square. Its also just a 7 minute walk from the central train station so very convenient for getting to and from the airport. If you time your train right, you can get from the apartment to the airport in under 30 minutes.
John & Ceca were the best hosts we've had yet on Airbnb, they fixed a small issue we had with the water straight away, and did everything they could to make our stay enjoyable. There were some nights that the noise outside was quite loud, but that will be the same in the centre of any city.
We'll definitely be back to Brussels and to John & Ceca's apartment.