It's a very atmospheric place. There are a lot of old books. Pleasant, responsive employees. We really liked it, even for a 10-year-old child. He especially liked the exposition, which shows how books were made: vises and so on.
A very good museum: I recommend you to visit. Entrance tickets are inexpensive. It is better (it is more interesting) to take a guided tour. You can also explore the museum yourself: there is information in each room. The museum has a decent souvenir shop.