The Christmas market is still going strong in Brussels and it will be until the last day, on January 5th. So there are still a few days left to see how incredible it is this year. Do not miss the light show happening in Grand Place. It will impress you beyond expectations. There is still the large Christmas tree in the middle of Grand Place along with an elaborate nativity scene.
Now that Christmas passed it's not as crowded although it all depends on what your perception of crowded is. But during the holidays there were so many people that you could not move while now that's not the case.