I generally prefer the discworld books that are more firmly part of an overall storyline, like The Watch, since they have such great long character arcs. But Going Postal is a masterpiece in itself imho.
Terry Pratchett was always great at making you empathise with flawed characters. Also, he was exceptional at creating "bad" or "evil" characters with believable and complex motivations, which never excused their actions.
So many of his villains are multi-faceted, so much so that you start to think he actually cannot write an unsympathetic "pure evil/Sauron" style villain, and then he hits you right in the face with Carcer or Gilt.
Truly a phenomenal author. It's fun to watch how his one-dimensional parody characters take on a life of their own over the series; you can really tell he has a love for them, even if they're not his cup of tea.
Yes, how much I hated them, they're just written so well!
And your other point also hits home, I've read or listened to pretty much all of the discworld books at least three times by now and I love it when I come across a character without a name who is just used as a throwaway joke in an earlier book, and then to realise that they are fully fleshed out in the later books.
"Me, i think. I've fallen into good ways. I keep thinking I can give it up any time I like, but I don't. But I know if I /couldn't/ give it up any time I liked, I wouldn't go on doing it. Er. There is another reason, too --"
"And that is -- ?"
"I'm not Reacher Gilt. That's sort of important. Some people might say there's not a lot of difference, but I can see it from where I stand and it's there.
"He was the company's chief engineer. He'd come with the company, and had hung on because at 58, with twinges in your knuckles, a sick wife, and a bad back, you think twice about grand gestures such as storming out."
