I can see us maybe taking a few games but winning the series is incredibly unlikely. Bruins are just too good, they do almost everything better. 1st in GA and PK%, 2nd in Goals. The only thing we match them at is our powerplay and offense (if it gets hot). Meanwhile, our GA and PK is at the bottom half of the league. It will take a hot goalie to save that side of our game because I don't see our defense as a group suddenly getting better anytime soon.
But even more in their favour is their team is full of proven playoff performers. Pastranak, Krejci, Marchand, Bergeron just to name a few have all had excellent postseason performances and overall solid playoff careers while our core has been dissapointing in that regard with a few exceptions.
Too much has to go right for us and I'm not holding my breath, but anything can happen. If we somehow managed to win the series it'll be the most impressive thing they ever did since their Stanley cup final run, but I'll be satisfied if they at least play their hearts out and give the B's a hard time. (Unlike the Tampa sweep)