I think the issue with many games, mainly shooters, is the sequel really is nothing more then a small new campaign, and some new MP maps (hello, COD)
I really don't get the comments re AC:B being like an expansion pack - as a game it is as big as the original (in fact for a similar % complete around 85% I put in MORe time in brotherhood as it was so good), has an all new storyline set after the first, new combat system, new brotherhood system (with assicated quest mini-games), all new VR training, all new MP that was built from the ground up, etc. Pretty much the only thing that wasn't new was the game engine and the name and backstory of the main characters.
I really don't get the comments re AC:B being like an expansion pack - as a game it is as big as the original (in fact for a similar % complete around 85% I put in MORe time in brotherhood as it was so good), has an all new storyline set after the first, new combat system, new brotherhood system (with assicated quest mini-games), all new VR training, all new MP that was built from the ground up, etc. Pretty much the only thing that wasn't new was the game engine and the name and backstory of the main characters.