Very clean and very quiet very secure location. Located on 4th floor accessible by elevator or stairs. We were a family of four, parents and 8-year old shared the king sized bed, the 14-year old slept on the fold-out couch.
We drove to Prague from Berlin: 1) make sure you get a toll sticker for the car BEFORE you cross the border into the Czech Republic (gas station or at last rest area just before you cross the border); and 2) in Prague park underground at the Pallidium Mall (3 min walk from the apartment) - we parked there for 3 days for 1400 CZK (long term rate automatically calculated at the payment kiosk, never needed to talk to an attendant).
Josef is a great host and always available to answer questions, even late at night when I couldn't figure out the lock.