It was very easy to get into every event. No problem what so ever. We did the city boat ride, field museum and the navy pier. I will definitely use them again in the future.
There should be a caveat on this pass. I was in Chicago in early March and the weather was cold and wintery. The Navy Pier attractions were not operating. We were on the Big Bus for maybe 20 minutes one day and the following two days, due to weather, it was not running. The pass is not clear if one can visit the same experience/site twice we arrived at the Art Institute about an hour before they closed and were told we could not use the pass again the next day. I paid for four experiences and felt I only used 2 l/4 the Big Bus being the fraction. Thus the 170 I paid for two passes was not worth it.
Highly recommend the explorer pass, save so much money compared to paying entry to the sights individually!