If you're planning on going to see War of the Worlds this weekend, do yourself a favour, and go see Batman Begins instead. Even if you've seen Batman Begins already, go see it again. Check it out on Imax if you can. Just don't go see War of the Worlds.
It's not that the movie's terrible, however it isn't very good. The overall movie just leaves you wanting more. The characters are all annoying, it seems to go on without any real direction, and the end is completely ridiculous. Tom Cruise is at his most annoying too, which is saying a lot. It's already got big opening day results (something like 21 million, a record for Cruise), but I say, don't encourage them.
Go see Batman instead.