The first time I was introduced to the work of Kevin J. Anderson was also the first time I read a lengthy novel, which was ALSO the first time I ventured into the extended Star Wars universe. The book was Dark Apprentice, the second book of the Jedi Academy trilogy (I think I picked the second book because of the cover). At the time I think I enjoyed the book, but mostly because it was a book about the Star Wars universe that I so loved growing up. I should point out that I was fairly young when I read this book.
Since reading that book, I eventually acquired a taste for what I liked in books, movies, anything with a plot, etc. I later read Anderson's next Star Wars book, Darksabre. It was that book that really gave me the whole "I hate Kevin J. Anderson" point of view; I really didn't like the story in that book, nor what he did with the characters. Going back to Dark Apprentice, I realized I didn't like what happened there, either, especially when compared to a fantastic trilogy like Thrawn trilogy Timothy Zahn put out earlier (which I must re-read).
I've always said - "I hate Kevin J. Anderson. I don't like his stories." I now realize that I'm being completely unfair to the man. I've only read two of his major novels, and a small handful of his Young Adult Star Wars books (which are actually pretty good for kids books). I've never read anything else by him. Who's to say that he's not actually a good writer outside of the Star Wars universe?
I recently both read and heard him state how hard he works as an author. He did the math, and figured that the average writer might take 1 full year to complete a novel. He is able to do that in 5 weeks (and I believe him - do you know how many novels he's written??). It's given me a new respect for Kevin J. Anderson.
Mind you, that doesn't mean I'm going to rush out and buy his stuff. But I am more likely to consider reading his books now that I don't irrationally hate him.