OK, I just saw this last night (I've been really busy, I still need to see Batman Begins). I liked it, but didn't love it. I'd give it 3 out of 4 stars. My gripes:
1. When the initial Tripod comes out of the ground, how are those 2 people able to use a video camera? ALL electronics are wiped out by the EMP, yet 2 cameras still work? Umm.... OhhhKaaay
2. I like Tom Cruise as an actor, but I can't separate his real life persona from that onscreen. To me it's like the movie stars Tom Cruise as Tom Cruise (Last Samurai suffered the same problem, IMO). I just didn't buy it that he was a rough and tumble NY crane operator.
3. I agree with what was said above, why did the aliens start zapping people if they wanted to harvest them? This is true to the book, but makes no sense. They have impenetrable defenses, so they should be able to methodically take over the world. I also REALLY wish the film would have taken place in Wells's 1898 instead of present day.
4. I HATED it that the kid survived at the end (I can't remember his name). There is no way that he survived that huge explosion, much less made it all the way to Boston past all the Tripods.
Overall, a good popcorn flick with nice effects, but Minority Report and A.I. are still my favorite modern Spielberg films. I absolutely adore Minority Report.