I'm of the opinion that, when it comes to creative works like this, there is no "good" nor "bad." Every single story is equal, whether it was written by somebody who has never seen a book before in their life or Tolkien himself (and I'm a Tolkien fanboy). The only thing that could ever even start to be objectively judged is grammar, and grammar rules are free to play with in creative writing so long as you know the rules in the first place. So, really, everything is good to somebody, everything is bad to somebody, and no story is better than another.
Now, as for what I personally like and what will keep me reading a story: characters. I never care about plot. All I care about are characters and how they interact with one another, hence why the Monogatari series is one of my all-time favorites. It's like 90% dialogue and bantering. Just give me more of some characters talking about whatever while going about their daily lives and I'll be happy. I'm also a huge sucker for romance and pretty much will never read anything that doesn't have romance in it.
As for what I don't like that would make me drop a story, inconsistency. Characters can be extremely unrealistic and their actions could make no sense, but I want them to be consistently like that. I'm not a fan of overly describing things with purple prose, either. In my opinion, simple descriptions that leave room for the imagination are the best.
So, to me, a readable fiction is one that heavily features interactions between a cast of characters who stay consistent with how they are written, and an unreadable fiction is one that spends too much time describing every little thing while taking focus away from the previously-mentioned characters. Give me less plot, less descriptions, and more banter. That's what makes a fiction truly amusing to me.