This place is a must see if you are a lover of architecture. This iconic building is situated in the most amazing setting. 360 views from both the exterior and interior of the building- it is a masterpiece. Some great photo ops with the great geometric forms of the building as well as views of rio in the background. The exhibits weren't too great, but I had read about that ahead of time so had reasonable expectations.
Definitely recommend stopping for a bite to eat in the swanky cafe/restaurant. There are 2 different menus with the cafe menu being more reasonable priced.
It was surprising not too difficult to get there. Take the ferry to niteroi, then walk a little to the right and you will see some bus stops in the center of the road. Take bus 47B (heading south) - the bus stops right at the museum - you will be able to see it from the bus easily. Note that this bus runs in a loop so just get back on at the stop where you got off to get back to the ferry.