I am kinda unenthusiastic about how BIG these games are, its becoming impossible to complete AC games without a crazy time sink, which for a series which has relatively regular releases seems a bit of a pain. I am sure I will get to it eventually as I do enjoy the games but I do wish they were tigher and more refined.
I am skeptical about the 4 player co op and hope it doesnt detract from the mission design, the games have been less about assassins and more about mercanary one man armies lately though so having a 4 man army instead will likely make little difference.
Don't buy it day one and just wait for a big sale on the gold edition.