The location is great, you can get to the apparment within 45 minutes from the airport using 1 bus line, btw oce you are there in five minutes u can get close to the Parc du Centenaire, wich is nice to visit in the morning, when there is not too much people there.
Furthemore there are a lot of places close to have your breakfast and get ready to start your journey.
Have fun in Brussels!!