Call me a numpty but I didn't realise that Pratchett actually sold diaries. Blank diaries for the customer to carry around and write important dates in. Sigh. I am publically admitting my ignorance in the hope of enlightening other poor mistaken souls.
I have come to the discworld fairly late on, enjoyed the history monks stories and thought I was getting another novel. There are a few pages of orignal fiction in the diary and the odd mildly humorous saying of Mrs Cosmopolite scattered throughout the book. But it remains, in essence, a diary.
If you are looking for a diary for 2008, you like Pratchett and don't mind flaunting this fact in public then you're onto a winner here. I wasn't looking for a diary, got hooked on reading the Lu-Tse snippets and so obviously couldn't return it then. C'est la vie.