Since the famous G-4 has not yet issued its evaluation of this issue, I will share some of my thoughts.
First, let me say that it is amusing to hear some politicians say that they are "shocked, shocked" to learn that this has been going on. Also, are they really surprised to find that a spy agency has lied to them?
Torture is abhorrent to American values. I think that we should never use it. Some argue that it produces actionable intelligence and should be used when necessary. The problem is that its usefulness is in dispute and that subjects often make things up to escape further pain. Even John Brennan, Director of CIA, admits that its effectiveness is "unknowable". Since there is no sure benefit, torture is out of the question.
We were wrong to torture other human beings. Who's to blame? Who should have been prosecuted?
The prime culprits were Bush and Cheney, not necessarily in that order. But no easy way to pursue them. Next, the lawyers who gave Bush and Cheney the opinions they wanted. These professionals should have been held to a higher standard than other actors. Censure, disbarment, or license suspension were possible appropriate actions.
The CIA agents who carried out the torture should not have been punished. They were complying with orders that they thought were legal. It would have been best for top CIA officials resign rather than carry out unlawful actions. Precedent was set when Attorney General Richardson and his deputy resigned rather than comply with Nixon's order to fire special Watergate prosecutor Archibald Cox. (who had been one of my favorite law professors)