It was great - we had 3 day passes and went all over Boston and beyond.
After purchasing and using the Go Boston card, I found that the attractions I used the card for were not as expensive as the card. Maybe if someone chose only the most expensive attractions to visit it would make the card worth it. It's hard to get the most out of the card, when attractions are only open/only accept the card from 10-5. This was not worth my money.
My husband and I enjoyed our trip to Boston and using our GO Boston card! The card got us in to all of the main attractions that we could squeeze into our short visit. The most difficult part about using the card was having to pick them up from Macy's. Don't drive, take public transportation!! Parking is very expensive and a big hassle! Aside from that, we enjoyed every minute of the Hop On Hop Off tour, Fenway Park tour, the Aquarium, the attractions in Salem (it was great that we were there on Halloween!) like the House of the Seven Gables and Witch Museum. We would definitely recommend the GO Boston card to anyone! We even got to see snow--an added free attraction!