Oh I loved Good Omens the four Bikers of the Apocalypse did it for me following the 4 horsemen bombing down the M4 so funny.
Small Gods did not like that much, Colour of Magic my 1st long time ago the parody of Fafhrd and the Gray Mouser in it brilliant.
There are two books that I dislike. One is Carpe Jugulum, which I feel is a rehash of Lords and Ladies. I think PTerry wanted to write the classic Vampire movie book and couldn't think of any other place to have than Lancre. It has all the same themes as L&L and situations.
Also Making Money was was rehash of Going Postal which the latter is a VERY superior book! I just hope that the next Moist book much better than MM. I was hoping the Moist would be a secondary character like William De Worde and make an appereance here and there. Since GP was such a tour de force for the stamps I felt that there was not may places for him to go. He was great in GP but almost one dimensional. He's a con man who had it coming and got what was coming and made good with it.
Can't read the first two any more, I just can't stand Rincewind, Twoflower bores me, & all the characters I love either aren't there or are unrecognisable. Also I didn't like Moving Pictures but I can't really pin down why that is
But the first time I read COM & TLF they blew me away & started something amazing, so there you go!