Most Helpful Guy
We can all tell you what makes book good, but that doesn't really tell you anything. What you really want to know is what makes a book bad.
The story line should be internally consistent. If magic works a certain way, or a detective uses some procedures, then magic should continue to work that way and the detective should continue to use those procedures or pay a price for violating them.
It's sometimes fun, as with the Hulk, to have a hero that basically just gets stronger whenever he needs to, but most stories have more believable heroes. Everyone has limits, and we can occasionally transcend them, but most of the time we succeed by working with what we have.
The characters should be somewhat realistic, but not too realistic. By that I mean, in our own lives random events just take place, and we ignore them because so much is going on. A story should flow, and avoid the realism of having random but unrelated events happening.
The characters should be realistic. Sargon, from the Lord of the Rings, was the embodiment of evil, as was Lord Sidious from Star Wars, so obviously, there's a place for unrealistic, one-dimensional characters, but most stories depend on people being people. It's rare that people are solely evil. As much as I loathe and detest Hitler, he loved animals and his girlfriend, and *in his own mind* (only) he was a hero, saving the only *true* human race.
Most Helpful Girl
Good moral lessons, doesn't follow trend, doesn't promote indecency; or something like that; such as emotional cheating, drugs etc