The place has a good location and it's fully equiped.
The entrance is a bit strange, through a gift shop, sometimes you have to wait for people to leave the shop to enter the building, but it's not too bad. The owner of the shop is very nice and helpful.
I don't really mind it, but there are a lot of stairs, especially if you're coming from the US bear in mind that it's closer to 6 floors than to 4, but if you're already in Lisbon 6 floors of stairs is really just a walk around the block.