(TLDR: Only fits two, read the house rules) While the location is good and the bed is comfortable, be warned that this space does not actually accommodate up to four people; no more than 2 grown adults could comfortably share this space. The sofa bed is one of the worst pieces of furniture I have ever seen, and it is awful to sit on let alone sleep. The third guest in my party had to rent a hotel room it was so bad.
Also, be sure to read the entire house rules before booking: you are required at check in to leave a 150€ deposit on a credit card before being able to check in.