He's always gotten on my nerves. I'm re-watching the whole series, and he's always been a "nobody-understands-or-values-me" whiny mcwhinernon. He just progressively got worse as the series went on.
Yes - people don't listen to him and he had been underestimated by many in the firm. He spearheaded the media department, was the first to go to LA to drum up business among other things. But despite everything, he's always been *just*so*awful. There's just something about how entitled he is and his woe-is-me attitude that rubs me the wrong way. When Cutler told him: "Are you aware that your self-pity is distasteful?" I cheered at the screen. When Roger just told Cutler to fire him last night: I yelled "YES!" . I know it probably won't happen, because Cutler is aware of his value to the firm and replacing him would be a pain in the ass.
I've wondered if Harry changed his attitude if things would go better for him. I think he's been envious of Peggy's courage (examples being when she got Freddy Rumsen's empty office or when she left SCDP for a promotion and pay raise because she was unsatisfied) and is very self loathing because he doesn't have the tits to do it himself. Thus all the man-whining. Am I alone in this? Gah, he's worse than Pete ever was in my opinion now.
ETA: After I wrote this, I found a GQ article that's just been written that asks: Is Harry Crane the most hated character on Mad Men. I guess I'm not alone :)