Finally got myself to a bookstore and tracked down the last two Terry Pratchett books. I had been warned that while they stand alone as reasonably interesting books, and by themselves are pretty good, on the pyramid of the DiscWorld series they just don't quite make it.
I'm 50+ pages into "Snuff" and so far it seems to be mostly a kind of catch up to what old fans already know. In other words, if you're a fan, you don't need to be introduced to the cast, and if you're not, it doesnt matter.
I also know that with a lot of the books in this series one needs to just plow forward and sooner than later it takes hold for the reader. We shall see (she said bravely)
Addendum: halfway through the first one, "Snuff" and it's good, it's thoughtful, a bit racier and more brutal than the others. Less humor, less slapstick, more sadness and anger; Im afraid the jacket blurb (as if the publisher had to push to sell this stuff) sort of goes overboard on the "hilarious hijinx" thing...