I posted already about whether the Iraq war was worth it. To really calculate that you need to know the costs and the benefits. Check out this study which shows how costly the war was.
Most frustrating figure:
Given how much of the reconstruction assistance was flushed down broken, misaligned toilets, I cannot adequately convey my frustration and outrage. More expensive than Japan and Germany combined, and so much was wasted through corruption, poor planning, lousy contracting, little oversight, and all the rest.
The ironic big winners from the war: cell phone providers as cell phones have gone from 80k to 23 million. To be fair, this figure shows other signficant improvements:
Water, electricity,and sewage are twice as available. On the other hand, more people are displaced despite the "stability" that has been created. That is really telling, as I have always viewed the flow of peoples to be the best indicator of progress or its absence.
If one considers success by the goal of stability, we don't know how that is going to turn out yet. I would bet on civil war, given the path of Iraq's government to marginalize the Sunnis.