This is my first Pratchett, and I had so much fun.
It was all the elements: the zanny world, all the stabs at our world's and several sub-types of fantasies usual conventions, Rincewind's quality of Luck's plaything and Twoflower's perfect embodiment of the "too oblivious and exited to get it tourist". And the luggage. The luggage was awesome, and the way it kept coming back the gift that kept on giving.
It ends in a cliff-hanger, but I'm not too anxious over it, because I was on the ride for the humour more than closure.
And apparently, this is not the best to be had in the Discworld... Sold on the author.