Personally, I have been a fan of the Assassin's Creed series since the first game. I did find the story missions repetitive but I loved being able to free roam and free run my way around and city.
With Assassin's Creed Brotherhood continuing the story on from Assassin's Creed 2, I'm quite excited and am confident that it will deliver a similar experience.
From the several hands-on articles I have read by gaming magazines, the multiplayer looks to be very suspenseful and is a great (but not tacked on) addition.