This is an old-fashioned monster-fest. It was fun to watch. A cotery of vapid friends party. When they wake up, all-powerful aliens are landing and taking everyone in the city away, using mysterious blue lights. Eventually, survivors of both the party and the initial landing have to dig deep and take on the aliens face-to-face and hand-to-hand, and we get a few hints of what both are made of.
What works: The visual and sound effects are pretty amazing. There is non-stop rampaging in and above the streets of Los Angeles. The alien monsters are appropriately monsterous and mysterious. What do they want? All the budget seems to have been spent on effects.
Not so much: the writing and acting are wooden. There is much posturing and arguing about staying or leaving. The aliens and their technology and biology are completely unexplored, even though it seems to be a key piece of their motivation for invading earth. Of course, both their techology and biology would probably not hold up under any sort of scrutiny.
I liked this more than I expected. With a little more attention paid to the script and a slightly higher caliber cast, it could have been a better version of Tom Cruise's ponderous remake of War of the Worlds.