Peter Harness has previously written for Doctor Who, a show strongly influenced by HG Wells. Unfortunately, his episodes tended to be a bit heavy-handed. Here, he moved the time frame forward from "the last year's of the 19th century" to "the first years of the 20th", and introduced a diplomatic crisis involving Russian attacks on fishing boats that quickly became irrelevant. Most of the episode was taken up with a soapy subplot about the relationships between the protagonist George, his mistress Amy, (not in the original), his estranged wife Lucy (perfectly happily married in the original), and George's brother (another new character). At one point Lucy (who will be conveniently killed off so that George and Amy can live happily ever after once the invasion's over - it has been clumsily foreshadowed) complained that she'd been replaced by someone younger and prettier, despite looking identical to Amy. All of this was based more on Wells' life than his novel.
There were also confusing scenes of two human figures wandering round what appeared to be Mars. These later turned out to be a flashforward to a Mars-like Earth, some years later. Again, not in the original.
There's a bit of a trend amongst adapters at the moment to take big liberties with the source material. ITV recently adapted Jane Austen's Sanditon, of which she had written so little when she died that it was all used in the first episode. And I gave up on the BBC's adaptation of Agatha Christie's The ABC Murders after a subplot involving Poirot having a shady past turned into a Message From Fred - "He's not Poirot." The overall impression is that adapters are more interested in telling their own stories than those they're working from. But if that's what you want to do, write an original story, not an adaptation.
The War of the Worlds is a classic for good reason. It's a foundational text of Science Fiction, the original alien invasion story, and a principled critique of colonialism. The best bits of the adaptation were those that stuck closest to the original. Peter Harness and the BBC should have had more faith in the source material.