This card is worthwhile. I purchased a 3day card and I went to the following attractions bean trolley, aquarium, whalewatching, Plymouth plantation, sky walk observatory, fine art museum and Isabella Gardner museum. So if you do the maths you will see that these attractions individual cost more than the Go Card.
Great Card and we definitely got our money back in using this card.
Can't honestly review this entire package. Didn't use much of it. So much is free in Boston, I would use that before purchasing this package. Beantown trolley hop-on-hop-off was the only thing we used that was disappointing, they showed up late often and not at all sometimes.