Remember HG Well's classic story "War of the Worlds". I read it, and it was a striking concept at the time. The idea of aliens from another world, coming to attack us, was such a vivid and frightening concept that it has influenced so much of science fiction concerning life on other planets. Aliens are either coming in peace, or coming to kill us; No two ways about it. Something that still remains in science fiction to this day.
Anyway, I remembered watching the 2005 remake with Tom Cruise. Let me say this off the bat - I don't like Tom Cruise. He's simply weird, even by Hollywood standards, and as a person who has to take prescription medication daily I found his views on medication to be offensive. Yet he wasn't bad in this movie. The movie, on average, was pretty good. The aliens retained their off-putting and weird nature, and iconic imagery like the Tri-Pod walkers remained. It wasn't the best remake, but it was decent.
What I didn't like about that movie, though, was it's ending. Here's a spoiler for anyone who doesn't want to know: The aliens die off because of germs on our planet. That's the original ending of the book as well - and back then it was another genius and fantastic concept - that Earth's simplest forms of life could defeat such horrible invaders.
Now, while I liked that ending, I didn't think it worked for a movie in 2005. By today's standards, the aliens dying of germs is simply bad planning on their part. I suppose another concept could have been developed to defeat the aliens. Alan Moore's "The League of Extraordinary Gentlemen" had a splendid ending to their second volume, which depicted the aliens invading Earth. They used germ warfare, attacking the aliens with the plague - and then had the cover story of normal germs doing this, to hide the fact they possessed biological weapons.
I suppose any ending other than the original one would have been untrue to the source material - but it really does strike me as shotty planning to not prepare for an alien atmosphere and possible contamination by germs.
Here's a trailer of the 2005 movie