Apart from not getting much advise on parking (two places nearby for reasonable money, I found a tip somewhere, but not from the hotel), the stay was great.
The welcome was great, nice personal, great to take the elevator instead of walking the steps. We had a room on the 5th floor next to the restaurant where the restaurant squeezed us in for a great dinner, the room was new, of course in a rather modern beton-style, good lighting all over, with lights on the bottom of the bed when you got up during the night. The view was magnificent and we could easily head up to the top floor late at night to take photos. The place is of course a very special place and the exhibitions also tell the stories. The surroundings have a lot of restaurants and also breakfast choices, and the Bunker is just next to the U-bahn, for very easy access to all of Hamburg. Now that we know where to park, we could easily come back to stay there again, as we felt welcome.