The interesting thing about Holden to me is how his attitudes, which were from the late 1940s, caught on in the late 60s. Salinger was, in a way, a prophet, I guess, at least as far as social change was concerned. His character was ahead of his time.
I think that Holden was probably depressed and out of sorts, but he has a poetic sensibility that makes him come alive--he values beauty and harmony, but does not know where to find it in a world that is scarred by war and atrocities. He says that if we drop another nuclear bomb, he wants to be sitting on it. That is a nihilistic point of view, but also brutally honest. Now we pretend these things don't exist and watch the Kardashians. At least he was honest.