Like all of King's books, this one is very violent and graphic at times, which can be hard to read, but I find that action is what makes the stories exciting.
I agree that it shouldn't matter if characters are gay or have a dark skin colour, but in this case the story is set in rural America (the Appalachians), where racism is still a pretty big issue. If they did purposely leave out the skin colour until later in the story, it would have been an interesting decision to make because of the context.
Also, there's the issue of imagining a character one way for most of the book, and then having to revise the image in your mind, which is a bit jarring.