I don't feel like I can give this book an actual star rating, if you know what I mean. Pratchett passed on in 2015 after the, "embuggerance," as he called it, finally got the better of him.
He did much in his life including campaigning for assisted suicide. An emotive subject from which he had an advantageous position in the discussion; ie. being well known and respected, his voice carried some weight and he could speak well.
My memories of Pratchett's Discworld series go back many years. When I was younger, reading a Pratchett book on a train was a sure fire way to be embarrassed as hell by the time I reached the final station. His writing was so funny that it was impossible to stifle a guffaw. Everyone else in the carriage would then look at me as if I was out of my mind. (they knew me too well!) Such was the power of a Pratchett book.
Discworld itself has been a growing environment. It has been a transformation. Sadly, it wasn't only the Discworld that transformed. Pratchett did also. His later works lost their sharp, observational humour and became more focused on the storyline itself. Not entirely a bad thing for a book, but it wasn't my original reason for picking up Pratchett.
To understand, "The Shepherd's Crown," it does pay to have read the appropriate books before in the Discworld series. The sub-wiki on the witches is here - https://en.wikipedia.org/wiki/Witches_(Discworld) - and that's quite a lot of books.
There are very occasional patches where Pratchett's humour does still shine through, however...
Then he shouted so that the rest of the clan could hear him, "This elf is oor prisoner. A hostage, ye ken. That means ye are nae tae kill it until ye are told." He ignored the grumbles from the clan. "As tae the rest o' ye, tak guard around yon stones. And if they come in force show them what the Feegles can dae!"
Daft Wullie said, "I can play the harmonica."
Rob Anybody said, "Aye, weel, I suppose that puts the willies up me, so wud likely keep them awa."
Not exactly rip roaringly funny, but gives you an idea of Pratchett's original sense of fun. One of the more enduring lines early on in his Discworld career being, "In some parts of the city curiosity didn’t just kill the cat, it threw it in the river with lead weights tied to its feet.." - more here - http://www.chrisjoneswriting.com/terry-pratchett-quotes/category/curiosity - and don't forget to check the categories on the right hand side for more.
Like many of the Discworld books, there are a fair number of characters involved, but it was one of his abilities to be able to have a high number of characters in the story and still the reader is able to keep track of what's going on.
The story doesn't really, "complete," for me. If you come in to this book without having read what comes before, you will definitely be missing things about You the cat and other odds and sods that make this book what it is. Even if you have read them, then there are still things left without being fully addressed. I still want to know more about Mephistopheles the goat, for example. Pratchett gave things special properties without adequately explaining them for my inquisitive mind.
The final battle was a disappointment. It was over far, far too quickly. The whole book had been building up to that point and I, personally, found it to be wanting. I had been growing disappointed with his later books. I hadn't really picked up a book of my own accord for more than a decade. I only read them when family and friends gifted me one for a special occasion; as this was gifted to me also.
I guess that as Pratchett's writing moved him to greater fame and winning literary awards for the story and plot... he lost that devil-may-care humorous magic that I loved him for. Every time I eat a curry, Death crosses my mind, stood alone in the darkness of Ankh Morpork. Don't worry... read Mort (book 4, I believe.)
To conclude I guess that, for me personally, this isn't the pinnacle of Pratchett's writing career. Is it a statement of his life, and a true and honest memorial to the man that gave the world so much wit and laughter? Very possibly so. If you're going to read this, I highly recommend going through the whole series. It is worth the time I believe, for what little my humble opinion is worth.