Bring a lot of time: this museum is huge! And a phone to help you reading the labels.
On the second floor there is currently an exhibition linked to Caravaggio. They brought a lot of paintings out of their storage for it.
On the first floor there is their permanent collection which also includes porcelain, statues, furniture and even whole rooms.
The third floor was closed. Why? No idea.
The museum is currently being renovated. I hope they will improve the lighting (a lot of glare on many paintings), the labels (way to small, only in Italian) and the toilets!