OK, so this should really be more about the misadventures and character development about the three friends. Because the whole premise about aliens and the "fight" against them only kicks in the last third of the movie. This movie's synopsis should really be about the comedic relationships of the three best friends.
And the whole point of the alien seems really tacked on for no reason, because the movie was going perfectly fine without it. It's all about these 3 friends who are constantly down on their luck and how things go from bad to worse from day to day. That in itself would have been an adequate premise for the movie.
That being said, it's kind of a funny and well-shot movie. It's just all the action scenes are terrible and the alien part is silly. The movie is still a fun time, but I feel that I was heavily misled by the description.