Since Amazon Prime (not Netflix) released their adaptation of Good Omens, I've watched it 4 times and read the book once. Let me tell you what all the hullabaloo is about.
I'll be honest: until a few weeks ago, I'd only read Neil Gaiman's Coraline, which was so eerie I had nightmares for a solid week. I'd never read anything by Terry Pratchett, but I had been in the same room as Paul Kidby, the Discworld illustrator, and that seemed good enough to me. I didn't have the desire to pick up anything by either of them, so imagine my surprise when I watched the Good Omens series and fell completely head-over-heels.
In case you aren't up to speed, Good Omens is about an angel and a demon losing the Antichrist and trying to stop Armaggedon from happening. As far as the premise goes, I'm sold. And while the show uses that as the main hook, the book is able to expand and explore all of the moving parts that converge at the end of the world. It's about an angel and a demon but it's also about the decendant of Agnes Nutter, the witch whose book of prophecy is 100% accurate. It's about the Witchfinder Army and the Them. It's about loving a place so much you can't let it go.
The book is written with an incredible amount of love and you can see it on every page as details and dialogue work to create a funny and lovely story. And I think that's what makes the show work so well. You can see just how much Neil Gaiman loves this story and loved his friend Terry Pratchett. Lines from the book are directly used in the show and very few details are left out. It also doesn't hurt that they have David Tennant walking around like he forgot how to use his legs and Michael Sheen doing an incredible amount of face acting. All in all, it's very good.
So do yourself a favor and check out Good Omens before watching the show. It's ineffably good.