Why locals love it
It's wild, huge and unique because it's so close to the city and it almost feels like a National Park in Canada (you won't see bears, I promise :-)) The rural surroundings (especially Dworp, which is the village I live in) are worth a visit too, you can still find local farms, old traditional pubs and restaurants, bright fields with animals,...
Why you should visit it
This forest is located in the greenest outskirts of Brussels (called 'De groene Gordel' in Dutch, which means, the green belt basically) and very close to the city (about 30 minutes by car). It's a young forest, which allows the sun to shine at the bottom of the trees, thus creating every spring a beautiful purple carpet of bluebells.
After a fresh walk in the forest, have a local beer/dish at the Smidse (http://www.desmidse1655.be/). It's a traditional renovated farm/paper mill