We traveled with two kids (2 yrs and 4 yrs) to Hamburg for 8 days and had a great stay in the Hotel. The design is very modern and quite unique. The beds a comfortable in a good size room and the window/view. Quite interestingly the room had a bathroom and a separate toilet, which is perfect for 4 individuals and looking at the hotel map it seems that all rooms have such amenities.
The location is generally excellent, despite the Reperbahn. 2 mins walk to St. Pauli train station or 5 min to the park or 7 min to the port.
The only down side is that the kids shared a bed, which they might be willing to do for 2 more years or so. Hence, I would only recommend this very cool hotel to couples with small children.
Probably the best hotel City hotel we stayed in as a Family.More