I very much fear that Sir Terry Pratchett's affliction of Alzheimer's Disease has begun it's inevitable and lamentable onslaught.
I just finished reading Unseen Academicals, and I regret to say, I don't think Pratchett wrote it.
I have no doubt the story is his, and that he was involved with the book's writing, but the book itself...
It didn't feel right. It didn't read like Pratchett's previous works. It lacked some... spark, some infusion of wit that used to lead to the smallest pune (or pun, possibly) being worthy of laughing aloud.
The satire was there; the keen observations of human nature, of the peculiarities of society, but the book as a whole lacked Terry's uncannily deep and lively touch.
I think I shall now begin a period of mourning that will last approximately the rest of my life.