Natalie goes to school, reluctantly, always hoping for a miracle that will restore her sight - or at least stop the deterioration. She's convinced that half of the classes don't apply to her, and hopes never to use the skills taught in the other classes. Whether she wants to or not, however, Natalie is learning important lessons about herself, about her abilities, and about friendship.
While Natalie has some complexity to her character, I should note that this is much more of an "issue" novel than Hamburger Halpin or Out of My Mind. As you may be able to tell by the summary, there is little else going on here other than Natalie's struggle with her disability. Cummings does an excellent job of presenting the practicalities of losing ones sight as a teenager - learning Braille, using a cane, relying on other senses - but considering they make up the bulk of the novel, it's a little short on compelling story-telling.
There's also far too much amazement at what blind people can do - walk a whole mile from the bus stop! Travel to Scotland! Learn self defense! While these facts can certainly seem amazing to someone without experience with disabilities, the repeated emphasis is patronizing and is part of what turns this more into an issue novel, rather than a coming of age story that just so happens to have a blind protagonist.
Cummings does do an excellent job with Natalie's voice. She is the right blend of bratty teenager and sympathetic narrator. 14 is hard for anyone - I can only imagine the difficulties with also having to adapt to losing your vision and changing schools. A lot of Natalie's frustration is totally waranted, and when she does go into extremes of anger or self-pity, well, that's what being 14 is about half the time. By balancing the extremes of negative emotions with genuine moments of compassion and kindness as Natalie grows, Cummings creates a sympathetic and realistic character.