Good movie, but disappointing in another cliche mood attempt by screwing with realistic color. Ever see such a drab battle in the vivid Pacific theater? Mostly muted browns and blues like Ektachrome 35mm slide film.
Granted, Iwo Jima was blasted to its core black and gray volcanic origin, but there is a lot more vivid blue and green in the Pacific. And scarlet blood, not maroon. Shooting through a dimming filter is not necessary.
It's unfortunate when even directors as great as Clint Eastwood think they have to parrot the prevailing era photographic history by copying only black and white or sepia tones or quasi drabs when those mediums merely reflect what were mostly the best available at the time.
One exception: horror films are always scariest in black and white so the imagination can run amok. Green is too much a basic life color to be frightening even in big lizards and vomit. For example, the original The Thing in b&w vs. its remake in color.
I'll give Saving Private Ryan and Guadelcanel extra credit for not doing the muted drab film filter.