My sister watched it tonight, and said it was a bit nuts. She says the interviewer was appropriately tough, and Ahmadinejad was flustered to the point that at the end he asked "are you from the CIA? I'm the President of Iran!" etc. The interviewer was also troubled by his smiling even at extremely serious questions, questioning how he could sit there smiling when he was being asked about these subjects; the interviewer also pressed him on whether Iran was making nukes, noting that it was a very straightforward question and Ahmadinejad was avoiding giving a straight answer.
My sister also noted that while she knew that he was twisted and crazy, it's quite another level to watch him in an interview. (Twisted and crazy in that he is clearly smart and knows exactly what he's saying... and what he's saying is nuts.)