Security concerns? A few...
Is this a good city for families/singles/couples? I was really surprised to find that couples seemed very happy here. The dating scene is very different from the previous unaccompanied posts I've been to as a single male. Baghdad is likely the only post in the foreign service where it is far better to be a single female than a single male. Beware the jokes for ladies when you leave Baghdad and land back in the real world.
What difficulties would someone with physical disabilities have living in this city? It might be a bit tough to get to the duck-and-cover bunkers. If you have physical (or mental) disabilities, this is truly not the place to be.
Interesting/fun things to do: Exercise, read, watch DVDs or go to the occasional happy hour.
What fast food and decent restaurants are available? A few sketchy restaurants in the International Zone.
Are local trains, buses, and taxis safe? Affordable? If you are looking to lose weight by no longer having a head and wearing a nice orange jumpsuit in the process, feel free to use local transportation.
How much of the local language do you need to know for daily living? None, though Spanish is actually very helpful here in the IZ.
Size of expat community: Absolutely huge. There are so many people here it is insane. There are always so many people hanging around the public areas near the palace that I wonder where I should work to have that much time off here.
Morale among expats: All things considered, it is okay. It gets trying, dealing with constant taskers from Washington that come at the end of the day or that you just completed for someone else. Hope that you have a good office that works well together.
Entertaining/social life: It's possible to be social and have fun, but it is far from being the best Post in the world to be a single male.
Weather patterns? Hot and dusty. Repeat X 365 days.
Recommended fiction related to this city: CNN and Fox News.
Any other comments: I'm glad I came when I did, but the sheer size of this place is insane. When you compare the size of Embassy Baghdad to Embassy Kabul, it makes absolutely no sense that Baghdad needs to be this big.