[S]o many of us are anxious to get the reader oriented in our world, and how it works, that we tend to shove too much up at the front. We don’t want to risk losing the reader, but also, we are so invested in our world and its workings that all our details are fascinating to us. Until the reader gets invested, it’s just more detail to try to figure out, while one is also trying to pick up character clues and hints about what’s going on. Thus a reader might get overwhelmed with stuff that will hopefully mean a lot to them as they get into the story–but at the beginning, one doesn’t know what’s important and what is just setting or backdrop Gulp. Holding hand up in guilt.I don't read much fantasy, but the same holds true for detective fiction. The author wants to get the character and the character's world out there up front and too often he bungs in some biographical or descriptive details that only serve to bring everything to a sputtering stop.
All too often, I've put down a book--never to pick it up again--because the author chose to spend a couple pages describing the main character's sandy brown hair or his extensive record collection or her offbeat lifestyle just as things were getting interesting.
One of the keys to becoming a successful mystery writer is creating a memorable character who can star in a whole series of books. So I can see how it happens. But the key is to show the reader why this guy is interesting by how he reacts to events. Not to tell us that he's interesting because he collects Miles Davis records or lives in a treehouse.