Over the years, you grow up, you mature and you see things in a different way, and it's reflected in the writing.
If you want to write about a person who isn't nice, people say, "This is a bad book. It's about somebody I couldn't stand. " But that's not the point. You don't have to like a character to like a book. Most of the time, people would misjudge and say, "I didn't like the book. " No, you didn't like the character. That doesn't make it any less interesting of a book. In fact, to me, it makes it more interesting.