I think the implications of only horizontal camera movement are very cool for this game. It really changes exactly how exploration can be done, as now I am forced to swim into an area if I really want to check it out. This really solidifies exploration--particularly, physically moving through the environment--as the mechanical center of the game.
Mouse look systems are of course easier to use for the player, but I don't think that an easier system like that is strictly necessary for this game. The camera as it stands right now does really work with the existing gameplay.
I like the underwater fog effect. I guess I can confirm it works on the Windows version of the game, on my computer. 😄