Apologies for the delay in posting this one up - I will also look out the previous thread to post the link back.
I really enjoyed this and I think it's because I hadn't read it 
Not sure how I missed it given I know I have read the next handful but it was lovely discovering a new one.
It was a bit too similar to the Colour of Magic as it focused so much on Rincewind and Twoflower (although I did like them both) and I'm still not too sure about the ending as seemed to build up to not very much. I did like the Great A-Tuin part of the ending but the rest...a bit 'meh' to be honest.
That said, finally finding out how the chief librarian became an orangutan made it completely worthwhile - I have wondered about that for years 