I finished GP a few months ago.
I know this is a fan-favorite and such, but to be honest... I was disappointed.
Let me be clear: I loved the character of Moist. He is fresh, entertaining, can keep the story afloat and has enough of depth to make it interesting. But his awesomeness can get the book only so far.
The plot was weak and incoherent. The whole post-office/letters idea was largely abandoned after the fire (such an obvious plot device... ergh). I didn't find the post-office engaging at all: Terry just might have skipped all that crap and focused on Moist being the fantastic bastard he is instead... wouldve been a great deal more fun (at least).
I also failed to get the book's central idea. What did Terry want to say with this one? The good ol' post office vs the big bad companies, who take advantage of the poor honest citizens? Isn't that one dimensional? Where's the conflict of ideas, usually present in Pratchett's books? And I'm not talking about Moist here: his development as a character was far more interesting than anything else here.
Don't get me wrong: GP is a great read. Very enjoyable, fantastic new character and the last 100 pages were a blast. It has a lot going on and most of it works. But for Pratchett standarts... lacking.
Give me the witches or Death! MUCH better.
"...my father is the Emperor of Klatch and my mother is a small tray of raspberry puddings."