I believe him. I don't think he's giving us the full story, but I also believe his explanations to be fairly representative of the real situation. The dude's never going to let out operational information that hasn't already been outed in one way or another, but a lot of what he's claiming is pretty easy to believe. He also needs to patch up the sense of mistrust in the relationship between hackers and the NSA because who the hell do you think the NSA hires? Lying to people who are the most likely to be able to see through your lies is not a good recruitment drive technique.
I don't believe him when it comes to oversight, and I don't believe him when he says judges don't rubber-stamp stuff. I think that there would be a few stubborn judges who understand that they're supposed to work for people, not the government, but the large majority would prefer to just let the NSA do as they please.