Brotherhood takes place in Rome while AC2 was in Venice. Although we now play in a new city, it could've just as well have been Venice, and much of the game really is the same old. Ezio jumps around the city rooftops and the storyline is one of treachery, betrayal and power in exactly the same way as in the previous games. The premise of the game taking place as a travel in genetic memories is still there of course, but really just a way to explain the boundaries of the game. Whenever there is something you can't do, it's because it's "untrue to the original memory". In that way Ubisoft have made themselves a great tool for explaining why you can't leave the city or do exactly what you want with the assignments you get. Hat off for at least trying to invent something new beside the "you wake up in a room and don't remember your name"-plot. It works and does what it should without interfering with general gameplay too much.
So, much in the game is like in AC2. You take assignments, jump around rooftops, blend with crowds, push people around and fight guards just as in the other two games. You can buy and build new features into Rome just as you could in Venice, where new buildings will earn you money and give you access to new weapons and armors, among other things. This feels more like giving the player both a way to earn more money, and have some way to spend it, and just as in AC2 this isn't what will keep you interested in playing. Yet again however, one must recognize the fact that Ubisoft are trying to make something new of a standard feature in many games, that of repairing and buying new items, by wanting to turn it into something more immersive and interesting.
The graphics and gameplay are basically exactly the same, meaning they're great. Just running around exploring is fun in itself for a long time, as anyone who enjoyed the first two games will know. There really isn't much else to say about them. If you've played the first two games you'll know exactly what Brotherhood looks and feels like.
We will get to meet Da Vinci again, who has a set of crazy inventions up his sleeve just as in the last game. They're both useful and fun, and do add something new to the old "jumping around rooftops" to keep us entertained for an extra couple of hours. His role is much as it was in AC2, meaning he's not a very important character to the plot, but rather some added flavor to the game as a whole. Da Vinci is far from the only character based of off a real person, in fact most of the important characters in the plot are based of people who once existed. Ubisoft have also implemented a data base with information about the era, giving the player a chance to educate themselves a little if they'd like to know more about the real Rome during these years.
But there are indeed some new features. Are they really good enough to warrant a playthrough, if you're bored with AC2?
The biggest change is the newly added Assassins Guild feature. Ezio can recruit his own band of assassins, send them on missions all over Europe, earning them experience with which you can improve their stats and gear. The more difficult the mission, aka the lower the succes rate, the more experience your assassins will get. As long as they're not on mission they can also be called in to help you out on your own missions, which can turn into a really powerful tool when used correctly making it a little more than just a mini-game within the game. It might not sound much, but it's just as fun as in any "collect and improve"-game, where Pokémon probably is the best example. There just is something really entertaining about taking care of your own band of Assassins, seeing how they improve and fight beside them.
They've thrown in a bunch of new weapons which are fun, but also adding to one of the biggest problems of the game series as a whole, which I've mentioned shortly . The new weapons simply are too good, making the player too powerful and the game too simple. One thing that made the previous games dull in the long run was the lack of any real challenge (remember Tetris again). Ezio is supposed to be a badass assassin of course, but there is not much fun in kicking the ass of everything you see and being practically unkillable, at least not in the long run. Since you can't restart a mission without dying, there are even situations where you will have to help the guards kill you, if for example you've failed wtih a mission and want to start over. They just can't do it by themselves. Much of the challenge in the game lies in completing the missions as close to perfect as possible, but there is no good way to restart them if you fail. If you simply restart them you start all over, clearing any checkpoints you might have made. The best way is to die, but like mentioned, that isn't always an easy task. Trial and error in a game doesn't have to be a bad thing, but it must be practical. In this game you rarely feel like you can be arsed to try to kill yourself to redo something, unless you really have to.
The game is designed to be played on both consoles and computers, but in some cases they've made too many compromises to have the game work with both. You can only assign four hotkeys for example, which in any computer game is just stupid. They've also chosen to map a lot of features to only a few set of keys, which makes sense on a gamepad, but not on a keyboard. Having three different things happen on the same key depending on where you do it is a great solution if you don't have many keys to spare, but it's a bad solution anywhere else. It tends to be a problem when your character burns down a building instead of looting a corpse, just because the key does both. Targetting can be somewhat of a problem at times as well. None of this ruins the game of course, but it's still annoying.
Another interesting design choice is that you can't save any progress yourself. This isn't an uncommon feature in games, and doesn't have to be a bad thing. Problem in AC:Brotherhood however is that the saving process is really subtle, probably in an effort to not ruin immersion, but it also makes it difficult to know exactly what progress has been saved and which hasn't. Overall you can be pretty certain that the game saves progress after you've succeeded with a mission or bought something new to the city, for example, but you can never be completely sure. It has made Love lose progress a couple of times, and can be somewhat annoying of course.
Overall, AC:Brotherhood is a mix of the old and the new, but mostly the old. It does retain everything about the old games, making it common ground for anyone whos played and enjoyed any of those. It does also add a couple of new features which makes the game a little fresh and interesting. The answer to the above question has to be - nah. If you're really bored with the first two games, this game won't be worth your money, but if you enjoyed AC and AC2 this game is well worth a playthrough.