The apartment is very spacious and reasonably comfortable - three sleeping spaces (though some are not entirely closed off, being above the living room) and three bathrooms (one huge, two tiny).
Location is great for living in Brussels - close to Ixelles, St Gilles, and a slightly longer walk downtown. Maybe not perfect for a weekend short stay, but nice for a longer stay outside the tourist area.
It is a nice apartment, and my lower review might be unique to my experience. The heat and internet were not fully ready when I arrived, and the heat was a recurring issue for a while. The internet, heat, a leak, and other maintenance issues had contractors in and out almost every week I was there (over several months). The person tasked with running the apartment was very responsive and helpful, but the apartment was simply not ready to be moved into when I arrived. Small issues were a constant issue across my three months there. Many of them are now resolved (heat/internet/leaks are all resolved)... but who knows, there were a lot of little issues and I wouldn't be surprised if there were more...