Doom? Foreboding? Vulnerability? I guess it depends on how familiar one is with the widely disseminated biographical view of Dean. I see an actor that liked playing in front of a still camera as a counterpoint to how serious he was about working in front of a motion picture camera. In the context of the large body of still images of Dean, particularly the non-candid images, one gets an impression of a class clown. Climbing into a coffin and donning a questioning expression is consistant with that understanding.
As for the photograph itself, it's unremarkable to me. It's value stems entirely from its celebrity subject. As stock, it wouldn't make it off the light table otherwise. Well, maybe by now as a "vintage" image it might.