This was brilliant!
Our drivers were extremely knowledgeable and friendly and the tour was just right for the amount of time we had in the city (one day). Particularly like the fact that I could get to Fenway Park (home of the Red Sox), but a shame the baseball season had finished! In the Summer you would get a harbour cruise included in the ticket, but since we were out of season we got two days on the bus for the price of one, which made it good value for money. Our second bus was full and as we went back into the centre it was not possible for everyone to get on board, so can imagine you might have to wait during the busier periods. The buses run frequently though, so just a minor inconvenience.
Definitely worth it!