Some folks complained when this first came out that "Battle: Los Angeles" was a little light plot wise. I suppose that's true. There's not much back story, character development, and all that. But really it doesn't need it. The title is "Battle" Los Angeles" and that's exactly what it is about. Aliens have come to kick our ass and kick it good. Our heroes are a mix of marines and civilians who are trying to survive and find some weakness in these invaders. Do you really need a plot, or a love interest, or anything else? This is basically one fine tuned action sequence with slow spots just so you can catch your breath.
The aliens are a little iffy to me. We are told they are powered by water, which seems like not the best source of power. Also the weapondry seems to vary in both power and accuracy. On the other hand I like how they build up. They fall as drop ship/meteors and come out as infantry at first. Then they start building up their command structure and technology and soon they are followed by flying drones and heavy artillary.
Certainly, all doubts aside, this is an exciting war film with a science fiction flavor. Well worth watching if you need your adrenaline pumped up!