The social commentary in District 9 was pretty ham-fisted. Like . . . they didn't trust the audience to make the appropriate associations w/r/t/ apartheid so they just set the thing in Johannesburg? I mean, that's just beating us over the head. The bad guys in District 9 were also two dimensional and absurdly diabolical. I'm talking like mad-scientist, James-Bond-villain diabolical.
Otherwise, though, it was pretty good. And the protagonist was the antithesis of the stereotypical action hero (he was a coward, and selfish, and cruel in the beginning). And, strangely, the same people who created the ridiculous villains managed to create a layered, complex human being for the protagonist. And we see a totally believable and compelling transition throughout the movie as his character is developed, responding to the ---smurfy--- things that are happening to him and rethinking things that he previously took for granted by virtue of being in the comfortable position of the oppressing majority and having never engaged in any serious ethical questioning before. Even by the end the protagonist was deeply flawed. He still presumably lacks empathy. The only reason he is able to consider what's happening to the aliens from their point of view is that it literally starts happening to him. That's maybe a step in the right direction, but it's a small one.
Anyway, like I said, I haven't seen Battle L.A., but it looks just awful. Even if I watch it and it's ten times better than I expected, it'll still not be nearly as good a film as District 9 (which itself is just pretty good, but not great).