I don't really agree that AC: III is worse than the other games... I think it is the best entry in the series!
Every time i play a game i look for a great story, and AC 1 and II have really weak endings, and in my opinion, a very lame main characters, ezio is a classic portrait of the "funny Badass" that will get the attention of any teenager for its lack of profoundness. Connor have a better story, a real motive, and the dangerous situations in the game feels much closer and more realistic than the others. The surronding story has better plot twists and all... I cared for connor. For Ezio... Not that much... As for Gameplay... why change what isn't wrong? And it added some really cool mechanics.
And to put an end to the rant, i am really scared of AC IV because it seems that ubisoft is milking way beyond what is excusable in terms of gameplay, and also it looks like it got back to the "funny badass"... i don't know... something feels wrong... I hope ubisoft change my mind as it did to me with AC III.