Tom Ricks is unsurprised by the news:
More evidence, I would say, that the surge worked tactically (that is, improved security and so enabled Uncle Sam to edge toward the exits) but failed strategically (that is, didn't lead to a breakthrough in Iraqi politics). I think the big question is how far the Sunni Awakening reversal will go. Is this the beginning of the next phase of the war? I dunno. And how much will U.S. troops be involved? Again, an open question. I am hearing through the grapevine that things are getting friskier.
Yglesias echoes:
We were able to stitch together some kind of peace and quiet that’s allowing the United States military to withdraw while holding its head high and claiming victory, which is fine as far as it goes. Still, there’s no genius “counterinsurgency” method here ready to be successfully deployed around the world.
The cult of Petraeus must be resisted. He is a gifted commander and took advantage shrewdly of several factors in Iraq to enable us to save face and get out as far as possible. But the surge was designed to create the peace for a national reconciliation and non-sectarian government. It failed. You just cannot change history or culture that quickly - or erase the memories of the carnage.