Yes. It had been planned for a couple of years by the director of the Southern Arizona Emergency Medical Services Council. Sounds like a success, judging from the sound of all the back-clapping going on.
I hate to say this, sorta, because any drill is better than none, but I'd be a lot more impressed with this drill if had involved a more challenging scenario in a different city. Say, a crop-duster or balloon dispensing anthrax spores over Denver. We might be able to get by a couple of thousand exposed people without panicking, but how about a million or so?
Doing a simulation like this is better than nothing, but it can't duplicate the panic and other emotion that might be associated with a real attack, and it also ignores any possible associated events (other simultaneous attacks, including possible disruption of the communications infrastructure or the power grid; people's personal concerns about the lives of their families; economic concerns as the stock market tanks; etc.).
Preparation is always a good idea, but war is one surprise after another, and it's a serious mistake if those in authority forget that.