I always give myself at least an hour for their exhibitions. I usually stay for 90 minites in the main exhibitkon hall right inside the entrance. I walked through the Bernstein exhibition twice.
I went last week. Unless they are adding stuff into the main exhibition spaces, a half hour is enough. As of June 25th, it was posters, set design artwork, photos, one video screen, and explanatory panels along the side walls downstairs near the circulation desk (including around the back corner) and a bit more on the second floor. At that time, anyway, the main spaces were closed for the teardown of the Bernstein exhibit. The R & H a small exhibit.