I think that was the right call. Pratchett's works after the Alzheimer onset weren't bad by any means, but they became very formulaic and didn't have the creativity of his best books. They're not helped by Moist van Lipwig being imo his most boring protagonist.
I really liked the first Moist von Lipwig book. The second one is ok. The third (Raising Steam) is just...bad. It's not funny, it's not anything. You can absolutely tell that Pratchett was losing his abilities.
To me it felt like he was hurrying to kind of tie a bow on Discworld and settle at least some of the longer-term plot threads he'd been playing with, similar to The Shepherd's Crown (which is better). The train theme of the book felt apropos, because he was loading a bunch of his characters on the express train to a reasonably happy ending.
I don't love Moist the way I do Sam Vimes, but the last handful of Industrial Revolution-themed Discworld novels are among my favorites. Maybe it's because I'm a software developer who trained in economics, but the discussions of monetary systems and public policy in satire is much appreciated.
