Nir Rosen has reported extensively from Iraq, and not only from hotel bars in the Green Zone. He knows what he's talking about. That's why the US congress invited him to give it the benefit of his experience.
This is what he told them. It may come as a shock to some people: the idea of a journalist not sucking up to the regime, but coming to his own conclusions based on (gasp!) first-hand evidence. Who ever heard of such a thing?