Card was a great value and we thoroughly enjoyed our tour guides who drove the trolley bus. The only problem we had was attempting to pick up our pass at the Viator/Trip Advisor office near one of the stops. Their was no admission allowed by anyone other than employees.
Very disappointed of the Go Boston Card service. They've made a mistake by activating our card with an old date, so we were not able to access our next destinations. It took us at least 2 hours to fix it by calling them and the call was in roaming. It happened with me and one of my friends, but entire group had to wait for us to fix the problem.
I would recommend to check for the date when you activate your Go Boston Card at the first place you visit.
Good way to catch the Hop-on-Hop-Off bus, city transit and access to many sites bundled into one. If you aren't going to use it for multiple days or several museum trips you may get separate tickets for less...but this was definitely convenient. I've looked up similar bundles for european cities London, Paris, Amsterdam and they are a great option for sight seeing.