Surprisingly unfunny
It's a step above Epic Movie or Meet the Spartans, but that's not saying much.
It was supposed to be an homage to the nuclear panic films of the '50's, but they made it too well. It could actually have BEEN one of those movies. There are so few jokes that it appears these guys were actually trying to make a serious 50's throwback film rather than a parody of them. If I hadn't recognized Robert Patrick, I might have believed that it actually was a lost film only just rediscovered.
A great opportunity wasted. What a shame.