In the PC primary season, it was said that those of us who spoke the obvious, that he's too frikkin old to be President, were discriminating against him because of his age. He's a war hero!
Yes, it is sad to see someone who was once quite sharp fade into the oblivion of old age. He's not going to be wandering the halls of his hometown tomorrow unsure of his name. He's got some time. But he's way past the age where he can be relied upon to consistently be himself.
I shudder to think of him in a high level diplomatic meeting, flipping out as crotchety old people sometimes do, on a head of state. I imagine him in a Cabinet meeting frustrated because he can't remember a word or a new capital city.
There are plenty of policy reasons not to vote for the guy, but I think his age alone should disqualify him. No, we probably shouldn't mandate a maximum age for Presidential campaigns, of course not. But we should judge on a case to case basis, and in this case, the McCain is too old.