I don't know why waterboarding is considered torture. You shouldn't try to invoke trivial moral principals when fighting an enemy. We are dealing with an enemy that is like Nazi Germany in regards to genocide and Imperial Japan's kamikaze suicide bombers. We should use pig's blood instead of water though. Use their radical ideology against them.
Having known several people who have served in branches of the military, it is my belief that it can be an effective method of interrogation. The morality of it is questionable and it has lasting effects on both the subject and the interrogator. Whether it is right is another matter; but it is without a doubt effective.
They have done studies on whether waterboarding is effective, and it shows that it's usually effective in a matter of seconds. Also, the good news is that a person doesn't really drown when they are waterboarded. They just think they are drowning so that they are willing to talk. It works.
No, torture does not seem like an effective interrogation technique. It will probably force someone to give answers, but how reliable will those answers be? If an individual knows that torture will only stop if they give the "right" answer, they will say anything they are told. But is it accurate?
Not only is torture immoral, but it is ineffective. When tortured, those captured would give the information that the interrogator wants to hear, rather than the truth. It also seems more likely that interrogators already have an idea of what they think the "truth" is, leading them to torture far after receiving the truth due to a mentality that anything other than the preconceived "truth" is correct information.