true, AC brotherhood is great, no denying that, but there is not as much to it as AC2. This is only in story terms however as the online really pushes it along, but it is more of a diversion than a vital sequel. I would not advise buying this particular set, as there are 2 lots of free DLC to be had on the Playstation store.
As a BETA tester for the online, I found it fantastic and fun to play, and I only got to play the wanted mode, and when I got the full game, it kept getting better.
This game does not have a lot against AC2 for the folowing reasons
1) it is exactly like AC2, but only with a few new ways to spend florens
2) it seems more like a diversion to fit in to the story and wrap up ezio's story before AC3 comes out
3) online is fun, but it seems like Ubisoft just wanted to keep up with its release rival, call of duty black ops
To summerise, I do think the game is good, but it is not the revolution of gameplay you would think it is, but there are a ton of new features, and yes, it has trophies to keep you going after the story is up. This has a nice look but the "exclusive content" has nothing on what the free DLC has to offer. If you are a hardcore fan, I would recomend, but for anyone else, I would say you should buy the game alone, and wait for AC3