Stayed here for a weekend.
The location is pretty good, close to both s- and u-bahn stations, four stations from the railway station.
Check-in was fast and very friendly, got a standard room on the 24th floor - pretty modern, good size, very nice view, comfortable, good wifi connection.
Did not have breakfast or dinner at the hotel so can't comment on the restaurants.
Often in hotels of this size, you get a bit macdonaldsy feel about the service you get. Definitely not here - everything felt friendly and personal. Really enjoyed my stay and definitely would stay again if I'm in Hamburg.