Terry Pratchett had up to 10 unfinished books left on a hard drive - now apparently crushed according to the BBC.
I've not read a novel in ages, but Ben had "Raising Steam" from the library to keep him company while recovering from his op recently, & I've been reading it now he's finished it.
Disappointing is a good word.
Basically it just seems to lack imagination: lets bring 19th century technology to the magical discworld. Also let Dwarves = Islamic fundamentalists, but let them just be cardboard cut-out characters, written from a deliberately myopic understanding of people.
Pardon the pun, but all the magic that was present in The Colour Of Magic has by now been thoroughly drained to create a society that kind of looks like ours, but one which can be used to protest about what's wrong with the world and where a main character falls dully and predictably in love. It's boringly moralising, despite trying to raise a sense of outrage at the mistreatment of (fictional) goblins, predictable and not much fun.
The more the Discworld has been developed, the less exciting and novel it has become. I'm not sorry there won't be any more novels from 'beyond the grave' (that's a phrase that should resonate with Pratchett fans) though if a different writer had been at the helm then perhaps they would have been more enjoyable.