Sounds like you are not a fan of one of the classics in regards to science fiction. Genres exist for a reason and new ones come about while old ones fade. Asimov was heralded because of the newness of the style of story and world created. It was one of his early works so yes improvement is obviously possible but not all stories are for everyone. Based on what you said stories without strong characters are not going to be enjoyable for you. Chalk it up as a learning experience for you as a reader.

Not my favorite but I will agree that Holden is a very interesting character. I don't find him relatable but I know people who act a lot like him. The book also touches several rarely written about subjects which is refreshing. To me it is targeting a teenage audience and speaking to what the world sometimes looks like through their eyes. This is why I think it is such a hit or miss book. If you empathize with Holden's world view you love it. If you don't then Holden is almost intolerably annoying.