Well, firstly, for me it was what I was waiting for. For me Crysis 2 is an evolution and a more mature version of the first Crysis. I understand that a lot of people expected the same game but with better graphics. It′s like to expect Metallica doing the Master of Puppets for their whole life xd.
I know what your try to say with "Alcatraz doesn't really talk much and that upsets a lot of people", but it's because there are two ways to develop a main character:
-A character with conversations, etc that is more like to see a film.
-A character in first person that doesn't talk, because the developers are trying to make you feel that you are that character, so if he talks, it's not you. His eyes are your eyes, his mouth, your mouth.
As well as that, he can′t talk because as Gould says, Alcatraz got deadly wounded, and that's why (spoiler) in the ending who speaks is the suit, because the suit has its (or his xd) own personality, Prophet, but not Alcatraz, he can't speak. It′s fun, it's similar to the couple KITT and Michel Knight xd.
I like that.
About the aliens... yes, you are right, and they could be more charismatic (well, actually they aren't charismatic), and the final battle is completely uninteresting. I wonder how they will evolve that part. In my opinion you can't put some maniac aliens like bugs. If their are so technological developed they should have some quite different behaviour... leaders, politicians... a society...