Cowboys versus aliens premise? Don't think I've ever seen those two together, might be an welcome addition to the weathered alien invasion plot movies and... cowboys movies? I don't dare say western spaghetti since it's obviouslt not. There are just cowboys in it.
Still, some great names there: Favreau, Spielberg and... crappy visual effects? I'm not one to bitch on the visuals but, damn, the spaceships bombing the town at 1:30 was just poorly done by today standards. I saw the same technique (or at least very similar) being done over and over again on Independece Day. And, God, do I see a rope pulling the cowboy at 1:33?