Well Pterry's books are silly. In a very intelligent and fantastic way, but still, I found the Kirby illustrations a lot more fitting than some I have seen since (the Harper Torch editions are just plain ewww !) and enjoyed spotting the characters and situations, although they were far from influencing the mental picture I got by reading the books, which has always been quite different.

But I agree, the cover won't stop you reading a book if you already know you
want to buy it. It might influence you one way or the other if you didn't know the author...