Saw the film today and while it wasn't perfect, obviously, it was very well done for what it is, i.e. a ground force invasion movie which only happens to be about aliens. Eckhart makes the movie - he is very VERY good in the role of the staff sergeant who does his best to keep the relatively new Marines (and their raw lieutenant) from feeling overwhelmed at their first taste of combat. The rest of the actors and characters are all cookie-cutter, as many reviews have stated...but honestly, except for Josh Hartnett, and to a lesser degree, Tom Sizemore, Eric Bana, and Sam Shepard, how many actors do you remember as characters from Blackhawk Down, which this film (Battle LA) is obviously mimicking.
The action scenes are very well done, capturing the intensity of firefights in an urban setting, where cover can be a car, a bus, or a partially blown-to-shit wall. The film wastes very little time on exposition so we know almost next to nothing about the aliens...except they obviously want to exterminate us and take over the planet.
Look...this is an action spectacle movie, nothing else (except, maybe, a nice recruitment film for the Marines, although enough of 'em die in the film that maybe not...). As such, it is LIGHT YEARS better than something like ID4 or many other big budget films. Because it is small in scope (only a handful of actors and only one locale), it feels more intimate. It doesn't matter if you "know" these Marines as individuals...after all, how many of the soldiers in Iraq and Afghanistan do you know personally, but their courage in fighting this enemy is admirable. And I know that sounds sappy, but the firefights are very intensely portrayed. Sure, there are some hokey speeches, but nothing as cringeworthy as, IMO, that horrendous "Tell me I'm a good man" ending to Saving Private Ryan.
It does suffer from a rather abrupt end and it certainly borrows plenty from ID4 in a way at the end (not as stupid as a computer virus, but almost as deux ex machina a device, in a way). It's nowhere near as flag-waving as ID4 though. And, IMO, it's a far superior film to Spielberg's War of the Worlds remake, which I enjoyed for the first 30-45 minutes or so and then it submarined into melodrama (I was hoping Cruise's character's whiny son would be killed).
Anyway, for me, I enjoyed it a lot. Saw in a very good theatre and as a digital presentation. Many critics point out how LOUD this film is and it really is all that! Is it SF? As much as W of the W or ID4 is...yes. In some ways, from a tactical standpoint, the aliens come off as plausible...their invasion strategy is spot-on. I don't think you can simply say that this could be the same film if it was human vs. human because the technology doesn't exist for a human army to invade on that scale that rapidly and that effectively. Is that enough of a SF element to justify calling it SF? Not for Roger Ebert, but for me, yeah. One things is for sure...like other "close quarters" combat movies, such as Blackhawk Down and the underrated Tears of the Sun, this will be best appreciated, cinematically, either in a good theatre or with a good home set-up, and no way will you get the sonic impact of the movie without a VERY GOOD subwoofer!