Boston is now probably the best beer city on the East Coast (it's a toss up with Asheville and Portland). And that's because, over the past 5-10 years, breweries have exploded all over the outer neighborhoods, pioneering the hottest style of beer in America right now (New England IPAs). These are places like Aeronaut, Trillium, Lamplighter, and Winter Hill Brewing Company - places that make excellent beer that's unique to New England, and places that are seriously investing in the neighborhoods around them.
Sam Adams ISN'T EVEN TECHNICALLY A BOSTON BREWERY. The facility in JP primiarly exists for R&D, and 99% of all Sam Adams brewed in the world is brewed in Ohio or Pennsylvania. Its beer is sub-par and it's as much a part of the authentic Boston community as the Cheers bar is.
This tap room will be a huge hit with tourists, but anyone who actually lives in Boston and likes beer will stay away, with good reason. Faneuil Hall sits right smack in the middle of a beer-drinking city, and will now prominently feature that city's worst brewery.