Such good fun. I think my favourite character was actually Dog. I loved the inner monologue that went with the Hell Hound!
I don't think I've read a story with so many characters intertwining throughout a story (though, truth be told: I've not read many stories!) - and this book did a superb job of keeping all the characters unique, interesting and coherent.
The story (for me), started fairly light (in heart) and towards the last quarter it goes rather dark - although this may be to be expected as the Armageddon is at hand. This also did wonders for my nightmares (I had three consecutive nights dreaming about my own End Of The World dreams).
I'm also really impressed that two different authors created the story in a way that feels completely unified (and this edition included a Q&A chapter at the end where Pratchett and Gaiman share their process and thoughts on each other).
Really fun stuff and included some real laugh out loud moments. The entire last chapter could have been highlighted too - beautiful closing message.