In reading "The Ones Who Walk Away from Omelas," what are the parts of the story that tell you how the writer actually feels about her characters...

The people of Omelas are are happy. If some want excess, they can have it. If some want simplicity, they can live that way. There are no structures in place to dictate how they should be happy, and the narrator suggests that this is how their happiness is achieved. But the narrator is continually defensive, as if we (readers/listeners) are thinking this is too good to be true.

O miracle! but I wish I could describe it better. I wish I could convince you.

The narrator is defensive because she wants to prove that the collective happiness of Omelas' people will justify the torture of that one child. This is where the author/narrator really expresses her assessment of Omelas' people. 

Some of them understand why, and some do not, but they all understand that their happiness, the beauty of their city, the tenderness of their friendships, the health of their children, the wisdom of their scholars, the skill of their makers, even the abundance of their harvest and the kindly weathers of their skies, depend wholly on this child's abominable misery.

They all know that their happiness depends upon the misery of one.

To exchange all the goodness and grace of every life in Omelas for that single, small improvement: to throw away the happiness of thousands for the chance of the happiness of one: that would be to let guilt within the walls indeed.

Since most people will not save the child and thereby ruin the happiness of all the others, they rationalize. They think that the child would not get much out of "its" freedom. Up to and following this point, the narrator is quite ambivalent about blaming the people. But here, showing their self-righteous rationalization of the necessity of this child's suffering, the narrator subtly suggests that this rationalization is unethical.

Le Guin brilliantly lets the reader decide what to think. She never fully condemns the people of Omelas, nor does she fully applaud the "ones who walk away." The story ends with the question: Is the happiness of all worth the tremendous suffering of one? And are the ones who walk away more heroic or ethical than those who stay?