I'm not saying that Cheney is right or wrong, or whether he told the truth or lied. I'm simply saying that he made an excellent, powerful presentation of his position.
The next step is to check into the accuracy of what he said, see whether his statements have any validity, and find out if he did lie and, if so, specifically where.
The main bone of contention is whether water-boarding actually did produce useful information and stopped any terrorist plots. Cheney and other right-wingers keep making these claims but, so far, I haven't seen any proof or verification to back up their claims.
Of course, Obama is raising a number of other valid reasons to oppose water-boarding.
But this is the main claim that Conservatives have and, so far, I haven't seen any proof that they are correct even on this point -- that water-boarding actually did thwart some terrorist plots.