I couldnīt care less if books are canon or not. For me itīs more important that i enjoy the book when i read it, than that it fits into a certain continuity and is a official part of the Star Trek canon history. OK, itīs great if you get a great read and it doesnīt contradicts the novels you have read earlier or the TV-shows and movies, but for me the overall quality is far more imortant than if novels are canon or not.
There is The Final Reflection for example. It was heavily contradicted by TNG, the movies and several novels, and itīs therfore maybe one of the most uncanonic (does this word exists?) novels out there, but itīs still a great novel.