Here's a link to an interesting and well balanced piece carried on the BBC news site - Haditha blow to new doctrine

For example, here is a quote from the piece, from an article by a senior British officer who served with the Americans in Iraq, writing in the Military Review ""The US Army has developed over time a singular focus on conventional warfare, of a particularly swift and violent style, which left it ill-suited to the kind of operation it encountered [in Iraq] as soon as conventional warfare ceased to be the primary focus."