Well, just as a comment, the impression of non-linearity I get from the game was more macrolevel than microlevel. That is, changes in the narrative based on your dialogue.
I sort of had the impression that the "combat" areas would be "somewhat" linear, with some variation on how to deal with the hostiles you deal with (sneak past, punch 'em, or pewpewpew). So I guess our initial expectations are a bit different