If it wasn't for the pass, I likely would have picked a different trolley company because this one didn't have as many stops as another company. With that being said, we used it as a hop-on, hop-off experience over two days. Our happiness with the trolley really depended on which driver that we had as we got on each time. Some were great - funny, historical info, kept talking. Some were just okay - talked more about non-Boston things or long pauses (like he couldn't think of what to say). Sometimes the next trolley came along within about five minutes. Sometimes we waited 15 minutes while other companies all came by more than one time.
Because it was part of the pass, I'm giving it a thumbs up. Otherwise, I wouldn't have found it worth our money.