If there are two exemplary alien invasion novels that come to my mind, Footfall is one of them (the other being Heinlein’s The Puppetmasters). The story is rather simple, aliens arrive in our star system, want to take over Earth and try to subjugate and/or exterminate the human race. The human race doesn’t take kindly to that sort of behavior and the aliens get their collective ass kicked by humanity (actually, it’s only Americans if I remember right).
When I saw ID for the first time I thought that it was like a cheap copy of Footfall. Not that I liked the novel, not all, I just loathe ID completely. Footfall has a big cast, but never made me care for any of the characters, sadly the aliens are even less interesting. They have been constructed in a certain way to make the story and their motivation to take over Earth logical, but I still thought it was contrived.
Couldn’t they have come up with something more original than space elephants, or at least made them interesting. There’s quite some big-screen action, people dying in millions, but somehow the whole thing was still boring. It’s as if they tried to write the exemplary invasion novel (which they got right), and forgot to make it entertaining.