For me, the 3rd installment of the saga, like its predecessor AC 2 played. There were also small (but nice) improvements in equipment (eg. As the Crossbow) and in the quests. The graphic makes no big jumps more forward what the game fun but not diminished for me.
Another plus for me is that the story of Desmond / Ezio continues seamlessly.
My conclusion: For all fans of AC AC Brotherhood is a (now cost-effective) must. The gameplay is at least as high and the exciting story goes to the next round.