I don’t often disagree with Roger Ebert’s film reviews, but it appears that he just didn’t get War of the Worlds. Ebert was looking for practicality and motivation on the part of the aliens, and was quite disappointed that the movie’s protagonists never learned much about them.
If the analogy hidden not far below the surface (no pun intended) means anything, it is precisely that it’s not always possible to know the motives of the attackers. In this sense, the creatures are somewhat like the one in Alien.
Anyway, “War” is pretty good. Leave it up to Spielberg to blend in the special effects so deftly, rather than making them the star of the show. I think he’s one of the few modern directors who can be trusted to render such a thought-provoking remake.