As mentioned in the review below, the building has not been used as synagogue for a very long time, but rather as warehouse and restaurant/ballroom. In the picture, you can still see the ventilation system from the restaurant. Because the building was no longer recognisable as a synagogue, it survived the Third Reich.
We visited the museum on a Tuesday to find out that the entrance was free (don't know if this true for every Tuesday), including a guided tour. The tour was given by two women, one specialist in judaism and one muslima who both explained the history of the synagogue & the rituals of both religions.
Although certainly interesting, we also feel that the site lacks outstanding universal value to be recognised as a WHS.