Its a tossup really. Its a massive improvement from ACIII but its still hung up in all the stupidly tedious trappings that are engulfing the franchise. The pointless side quests, the on rails tailing missions, the multitude of ways to make money thats difficult to spend on anything worthwhile, and snoozefest that is the combat system. And of course you couldn't be bothered to give a crap about either the meta story or Kenway's story because no one has any character and none of the ideas explored are very interestingly executed.

ACBF worth it?

I just don't want them constantly popping up while I'm playing a game is all. I couldn't care less about achievements.

Nice achievements mate -.-