I am really interested in the game because I really liked the first two, but I am worried about how it will be solo because co-op really is not my thing.

Its basically like Army of Two of co-ops, in which you can only really enjoy the game with another real life player, if you play solo its just you, no AI buddy and the game is REAAAAALLLY action oriented and the least scary game of series yet 

The game still feels like it was meant to be played solo. The co-op just seems like a well-done bonus.

@kmg90 said:

Its basically like Army of Two of co-ops, in which you can only really enjoy the game with another real life player, if you play solo its just you, no AI buddy and the game is REAAAAALLLY action oriented and the least scary game of series yet

I would say the opposite. While the co-op focus is clearly there, the slow pace and story elements really drag it down when playing with someone else. It feels more like a singleplayer game to me but with co-op added on, sort of like Halo.