I am sorry to hear this as well. I have not always agreed with him politically, but I have always respected his integrity, his willingness to speak his mind.
I was very moved by his speech in 2008, probably his nomination speech at the Republican Convention, when he said, referring to his POW experience, torture, for which most of the country so greatly respects him, "They broke me."
I thought that a very brave thing for a war hero to say, on national TV, while running for president, and I really respect him for saying it.
Also his statement on the advisability of "enhanced interrogation" of captured terrorists: "It is not about them. It is about us."