Oh, but I didn't like
The Colour of Magic that much (I know, heresy!) I'd recommend
Good Omens (written with Neil Gaiman), and also
Wyrd Sisters, which was snort-tea-all-over-the-ebook-reader funny.
You might like
The Colour of Magic more than I did, though. I guess my point is that even within the Discworld series, there are different strands, and if you don't like one set of characters, you might well like another. (I'm a huge Granny Weatherwax fan, myself.)
The good news about all this is that he was diagnosed early and there are some pretty good treatments available these days. Also, research is showing that staying mentally active is very good for postponing memory loss, and I think we can safely say he does that!
BoingBoing had a post about this recently with some great comments. Including one little vignette about a large room with shelves of hourglasses....
