To start with, it's from a collection of books called Discworld, and is the 33rd book in that series. I know nothing about those stories, but especially given that Mr. Pratchett has other books beyond just those in the Discworld series, he clearly was quite a prolific fellow.
What I do know something about, though, is the two-part film of Going Postal which I found to be an utter joy. Good characters, enjoyable drama, overwhelmingly inventiveness and generally very funny -- and a seriously-impressive production, most especially for TV. It has somewhat the sense of Hitchkiker's Guide to the Galaxy, though with more of a direct story Basically, it's about a light-hearted con man who is caught and given a choice of sentences -- death or postmaster on a very distant barren land. Not surprisingly, he selects the latter, although it's a no-win, disaster of a hellish job. His life if further conflicted by a devious man who wants to take over the land, against whose plans the con man unknowingly stands in the way, and there's also a highly-belligerent woman fighting him at every opportunity, until she finally grudgingly changes course because she hates the power-hungry villain even more..
The cast is wonderful. Oddly, the only main character I don't know is the actor in the lead -- Richard Coyle, who's had a successful career in England and done some several things done here in the U.S, though I just couldn't place him. But he's excellent. As for the rest though -- the main antagonist is the wonderful David Suchet, best known for starring in the long-running PBS series of 'Hercule Poirot.' stories. Playing the young man's adorable, overworked, eternally good-natured assistant is the great Andrew Sachs, who most people would likely know from Fawlty Towers as John Cleese's put-upon hotel valet, 'Manuel.' Throw in Charles Dance, who tends to be in about every third production on PBS Masterpiece. And then, as the belligerent young woman, she's played by Clare Foy who came to fame as the young 'Queen Elizabeth' in The Crown.
I found the series a total, non-stop joy. Smart, vibrant, well-acted, clever and a huge, impressive production filled with inventive special effects (creating at times sort of modern-day technology in a old world setting) -- along with a very good story and over-loaded with humor. It may not be for everyone, since for some people off-beat fantasy is not their cup of tea. But boy, is it well done. It has 8 starts out of 10 on Netflix, and a 7.8 rating on iMDB.com. And 4.7 stars out of 5 on Amazon Prime. So, as I say, I tries nots to steer you wrong.
I'll note that if you're enjoying Good Omens, although the story is completely different, the style and sense of humor and whimsy is similar.
You can get it on Netflix here. Or at Amazon Prime here.
(Side note: If you do watch it, know that author Terry Pratchett has a tiny, but fun cameo in, I believe, the very last scene, playing a somewhat befuddled man, looking a bit like Santa Claus.)
They do a good job with the trailer. But I can assure you that no trailer, no matter how energetic even this is, can come close to doing it justice. But here it is anyway.