Well, few surprises in this movie. Alien invasion, or is it? A smart scientist figures it out, sinister gummint organization, nuclear weapon launched, abort sent, etc, etc.
The characters - almost every one of them was over acted. The hero, with his Clint Eastwood breathy voice. His wife, the beautiful doctor with always-perfect hair and makeup who works in a public hospital: puh-lease. The slavering general. Cardboard cutouts, every one of them. Grace Phillips in her braless strappy top (and to her credit she looks OK in it) gives some idea of where one of the target demographics of this movie was. The female mud-wrestler type cast as a security guard could be another clue. And almost all the other women, who for some strange reason had short skirts and very high heel shoes, might be yet another.
Special effects were reasonable, although the multiple alien spacecraft sitting in the crater, each one an obvious copy/paste of each other... at first, I thought it was a computer wallpaper. And the stories with the nitrogen inhalers - please, give us nerdy audience types at least a tiny sliver of background knowledge.
I think that the worst sin this movie committed was that it couldn't make up its mind as to what combination of seriousness and comedy it was going to be. But again to be fair, if you set your expectations low enough you might well be entertained.