I was about 30 pages into it the first time I gave up. I started again after a few weeks and this time got about 40% through. It's not a bad book. There's some great walk-on parts with some of my favourite characters and the story is ok, it's just that I feel it's all a little hollow really. At the same time I did kind-of enjoy what I read. It's just that it simply didn't draw me in the way I'd like it to have.
I'll definitely read this at some point. Probably in the not too distant future too. It is a Discworld novel after all's said and done.
Maybe I just need to be in a more Discworldy frame of mind first.