Sam Adams has done an amazing thing - opened up the world of better beer for millions of people.
For most of those people, it's Boston Lager. They hardly realize there are other styles of beer than lagers. (Dark beers?)
OK, I don't usually buy Sam Adams beers(well, I did get some for Octoberfest). For almost every style they make, there is a better example from a microbrewery. Will I drink a Sam Adams offered at a party or a friend's house? Yes! Will I drink BMC if that is all that's available? NO!
Most that don't like Sam Adams either:
1. Don't like the style of the beer in question and are comparing to a different style(that they like), or
2. Are comparing to a great microbrew or homebrew.
or both.
Sam Adams makes a credible beer for every style they make. They are a big company, however, and seldom match the best microbrew or homebrew available. Heck, I can't find any poured beer in Nevada that tastes as good to me as my standard IPA or Pliny clone I make. But that doesn't mean I don't enjoy a well made commercial beer.
I would agree with this, Sam Adams is good for the money but when comparing too a hand crafted beer that isn't mass produced, well that's a whole different ball game.