John Kiriakou was on the team that interrogated al Qaeda capo Abu Zubaydah. Kiriakou says that he did not waterboard Zubaydah but did question him. According to Kiriakou, Zubaydah was uncooperative for weeks after his capture, willing to discuss the finer points of Islam vs Christianity (probably attempts to proselytize his captors) but would not divulge a thing that he knew either about al Qaeda or about ongoing attacks. Waterboarding him changed that in 35 seconds, and Zubaydah became a most cooperative witness. Kiriakou also says that the destruction of the CIA’s interrogation recordings should not have been done.
Kiriakou also says that waterboarding was necessary early in the war but isn’t now. Like all complex issues, this one is worth looking at in the full context of the kind of people we’re dealing with.
CNN has set up its page so that links to it will take you to two videos, the first a description of waterboarding and the second the interview with Kiriakou.