I’ve tried a number of times over the years to read Terry Pratchett, without success or a great deal of enjoyment. But that may be a result of my starting with the early novels, when he was still learning the craft. In any case, he has now clicked for me in a way that promises much pleasure in the future, so hooray for that. And I find this 2017 post from Adam Roberts enormously helpful in getting a handle on Pratchett’s distinctive value as a writer:

I didn’t know Pratchett personally, although I did meet him a few times at publishers’ dos, bookshop events and the like; and once I was on a BBC Radio 2 bookish roundtable with Simon Mayo, China Miéville and him. And I know people who did know him, with varying degrees of intimacy. When they talk about him they do so with love, and loyalty to his memory; but one thing that comes up is how unlike the cuddly humorous old granddad popular-culture version of him he was in life. He was, I have heard more than one person say, capable of real and focused anger. Injustice and unfairness made him angry. There are many things to say about his novels (and to be clear, before I go any further, I should say I consider him clearly one of the most significant anglophone writers of his generation) but the two things that stand-out for me most are: his extraordinary command of comic prose, a very difficult idiom to master and doubly difficult to maintain at length; and the repeated and unmissable ethical dimension to his writing. He was a moral writer above all, arguably even before he was a comic one, and certainly (I think) before he was a worldbuilder, or a creator of character, or a popular metaphysician about gods or existence or death or anything like that; important though all those elements were to his writing. Nor can his moral purpose, and his anger, be separated out.