I have been here twice - once for the Munch exhibit and and once for the Jeff Koons exhibit. The exhibits themselves were great, but there was minimal information available, and hardly any information in English (or in any language other than German). The audio tours only came in German and the special books on the exhibit only came in German, too. The books looked fantastic and were reasonably priced and I bought them, hoping my husband could translate some of the information. I was very surprised about the limited English information as the exhibits were world-class and Frankfurt is such an international city.
The museum is easy to get to (right by historical Frankfurt) and is worth a visit, just understand that you won't learn much about the exhibit, unless you speak German (so maybe study ahead of your visit). In response to some of the other reviews, the staff with whom I interacted were friendly enough and would double check to make sure there weren't English versions available.
One other note - you can visit the museum with a stroller (or at least I could), even a double side-by-side stroller, it's just not easy to find the small elevator or navigate within the museum so you will have to ask for help.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC