A great addition to the Assassin's Creed franchise!
Though ACB is mainly set in Rome, there's still much to do. Rome is huge, and comes with a variety of different areas. There's plenty of scenery, such as the Colosseum, St. Peter's Basilica, and much more.
What makes it better is that you can even buy these buildings! The economy system is vastly improved over AC2, with much more importance. Each district in Rome has Borgia Towers, which forbid the renewal of shops and other establishments which provide the main funds to your war effort; the money gained from missions is no longer the main contributor to your equipment.
Destroying these towers also grants you the ability to recruit and train your own private army of badass assassins. With each tower gone, you get one more potential recruit. I think this is a great addition to the game as it allows you to earn money by sending these guys on missions, and it lets you get out of a potentially fatal fight.
There are other significant improvements over AC2. Free running is not as simple as holding "RT" and "A" for the whole duration. Timing your jumps and climbs is quite important for momentum. It's much easier to die falling off a building now. Quick descents have to be made only via a leap of faith or parachutes, which I think compensate for the change.
Combat can be both easier and harder than before. There's a variety of new weapons, including crossbows, poison darts and heavy weapons. When fighting guards you can perform one hit kill-chains. This is especially useful when guards are attacking en mass, giving you an opportunity to confuse and decimate them within seconds. But there is a risk. Guards do not attack one by one as they did in AC2. While you're blocking the attacks of some swordsman, a guy with a spear could be aiming for your back at the same time.
The characters are well written and acted out, which makes them quite memorable than most in other games.
The soundtracks is awesome too, bringing back that kinda "nostalgic" (for lack of a better word), and authentic Renaissance feel that AC2 had.
Now moving onto AC's newest feature... multiplayer! While most MP's this generation are focused on going in all guns blazing Rambo style, that is not the case with ACB.
ACB offers a unique experience, with focus on tracking and evasion strategies rather than direct engagement, because there is no direct engagement.
Players are given targets, which they must eliminate as stealthily as possible. Given that the maps are filled with tons of doubles of other players, people must rely on a compass device to find their target. If a civilian is killed instead of the target, that target is lost and replaced by a different one. If the target detects you, a chase sequence ensues instead of a fight. If the target escapes, you get a different one.
The MP is brilliant yet mind boggling at the same time due to the fact that the hunter can turn into hunted in the blink of an eye.
I won't go much further than describing that particular game mode, because I could be writing for ages. The multiplayer is fresh and unique, something new in the mostly FPS dominated territory.
You may wonder why I gave this game 9.5 when AC2 got 10. IMO, AC2 has a little something that makes it a bit more enjoyable. But anyway, ACB is a fantastic game, and is definitely worth the 50 euro. You won't regret it! :D