Museum Brasserie is one of those much-hyped restaurants that disappoints a bit.
Right on Place Royale, Museum Brasserie is a trendy restaurant frequented by patrons of the arts and Bozar concert-goers, which might account for the somewhat inflated prices.
The food is good (modern Belgian fare) but not worth the prices they charge, and nothing is really so memorable that makes you want to go back. (I cannot remember what I had, but I do remember nothing struck me as great).
Perhaps one of the most interesting things is the decor, which is best described as trendy-semi-minimalist modern meets classic Belgian setting (with the high ceilings of an old Brussels building which make the restaurant feel quite open and spacious). However, this is something you can find in many other Brussels restaurants as well…
Having said that, it is probably still worth a try if you can get the 30% discount with the Restopass.