It might just work, if Spielberg keeps the atmosphere of hopelessness and powerlessness that pervades the book. The adventure apect of WOTW has already been explored, and is limited. I mean, Wells made these aliens eat human flesh and drink blood, so they're not nice things. They're intelligent, ruthless, and totally alien.
All of the emotional aspects of the book should be put on screen - the fear and suspense of the alien's arrival, and the utter hopelessness when mankind is swept aside easily by the alien war machines, and the dispair when they know their world is gone. Spielberg can portray these things, and well - but will he? Or will he make a lame special effects driven travesty like the Matrix 2 and 3?
Things he IMO must avoid:
- American accents. Nothing ruins a period drama than an accent out of place or someone trying to do a fake one. Keanu Reeve's accent in Bram Stoker's Dracula makes me shiver more than Oldman's excellent performance as Dracula. The idea of Cruise playing anyone but an American in the story makes me shudder even more.
- Making an adventure or action film out of it. Jackson did this with LOTR and trampled most of the book's subtleties under his big New Zealander boots.
- Too much CGI. It's still not at the point where it looks believable. And wide cinematic shots over the landscape to show off would just make the film look like a computer game.
- Hollywood cliches. That means all of them. Wells knew what he was doing, follow him and not the cliche route.
