In looking at the situation in Iraq, are we seeing a precursor of things to come in Afghanistan?

In Afghanistan we also have a society without a history of democracy; an ethnic tension that has not been lessened over the years we have been there; a President who has more interest in consolidating power for himself and his party not unifying the many tribal factions into a single power sharing central government; an army of questionable skill and commitment that has not exactly shown the ability to be self sufficient let alone a potent force for good; a well organized, armed and funded foe of the present power structure, in this case the Taliban, waiting in the sidelines to regain power once the US leaves; and surrounding countries that could benefit from the downfall of the present government.
Should the US learn a lesson from Iraq? Is it that we need to stop wasting our manpower, money and resources immediately and just leave now or are there things we can do differently to insure we do not witness the same disintegration of the government we have propped up for the last 12 years? And, will it be worth the cost?