You've seen the original War of the Worlds, right?
It was kind of an insult to the book. By the end of the movie, you could swear that the Martians were prayed to death!
Interestingly, the Spielberg remake was actually truer to the story, but ruined by changing the main character from "separated from wife during the first attacks" to "father of two stupid and incredibly annoying brats". Dakota Fanning's character is a jackass that adds nothing to the plot. And then they had to stick the stupid family plot at the expense of cutting out better stuff: the main character's brother's adventures are mostly shaved off and partially added to the main character's plot; they also fused the likeable drunken artillery soldier with the least likeable character: the despiseable vicar.
But all in all, it was kinda truer to the book.