One of my most favourite authors, I'm a huge fan of his writing style, in particular the Discworld novels but have also read The Bromeliad (Truckers, Diggers and Wings) which were also cleverly written.
I've also enjoyed the adaptions of Hogfather and The Colour of Magic/Light Fantastic. I hope one day a film will be made of one of the Guards stories. Would love to see Carrot Ironfoundersson acted - wonder who could play him.
Favourite characters in Discworld are Detritus, Gaspode (woof! bark!), Greebo, DEATH, Nanny Ogg and Lord Vetinari.
I like the way in many of Terry's books he can take a situation in real life and "fantatsise"/plagiarise it - make what is in the an analogy of real life, and like to try to spot some of the jokes as references to real life.
Saddened to hear he's suffering from Alzheimers and possibly won't be able to write for much longer, I hope things won't get too tough for him as he's given a lot of enjoyment to a lot of people with his writing.