In my opinion, Boston is not a very stylish city... or at least not a city where people take a lot of style risks. I guess it all depends on what you think is stylish, but it seems to me here that people really follow the trends of big labels and try to emulate "celebrity style".
Boston is trying to make itself recognized as a stylish city, though. A few weeks a go in the Globe was a list of the top 20 stylish Bostonians and right now at the MFA there's the Fashion Show exhibit. But I really don't think that all of this, plus the prescene of luxury stores, is going to make Boston a more "stylish" city. The majority of Boston women I've seen all wear designer denim, wear pointy shoes and have Chloe or Gucci bags. All the girls my age wear Juicy, UGGS and have Vera Bradley bags (
) Although there are stores in Boston that carry what I believe to be more stylish clothing (Louis, Alan Bilzerian), I've never seen anyone wear something like that. For evening, women here seem to be either wearing something conservative or in the vein of Valentino/Dolce...
Honestly, I think if you want to find interesting Boston street style, go to Cambridge.