The aliens are hilarious.... They seem to be animal/machine hybrids with automatic weapons growing from their arms, which must make it hard to change the baby.
Actually this isn't so bad of a movie if you aren't expecting an original plot, great character development or sparkling dialog. But it does have great action, gung-ho Marines and some nice helicopter scenes. Any movie with gangs of helicopters is alright in my book.
(PS: Did you know there actually was a "Battle of Los Angeles," during World War II?)