The Good Stuff

I base my criticism on 5 principles of good YA fiction. Tell me what you think in comments. What makes you keep reading a book? What counts as "good"?

1. An engaging protagonist. All YA novels have protagonists that are 12-21 years old, but that's just a guideline for the genre. The protagonist in a really good novel will be fundamentally likable for starters. For example, Clary, the protagonist in City of Bones isn't always likable because her spinelessness and dullness is frustrating to the reader. In contrast, Katniss Everdeen is a likable character because of the way she treats her younger sister and her determination and bravery. An engaging protagonist must also have faults. Teenagers feel vulnerable, even if they pretend not to, so a character with a weakness or flaw will feel authentic to the reader.
2. A fast-paced plot. YA fiction often starts with an inciting event: something that creates a before and after scenario. Also, YA novels usually tell a story in a short period of time. Before I Fall takes place in seven days, Harry Potter is only during the school year, Hunger Games is less than two weeks. Unlike adults, who tend to think in long-term consequences and timelines, teenagers usually only see the immediate effects and events. A good YA plot will move quickly from event to event, without a lot of background information, discussion of the future, or explanation. 
3. Underlying Morals.  A really good YA novel will show the protagonist turning away from childhood and stepping into adulthood, without telling the reader to "grow up." The moral should be there, but not on a billboard with flashing lights.  
4. Few sub-plots, if any. YA novels are very non-Dickens. There should be one protagonist, one antagonist, and one climax. Adult characters tend to take a backseat, as do other less important characters. Just like teenagers think the world revolves around them, so the plot centers around the protagonist. Writers are often tempted to try too many things in their 300 pages, and it always ends poorly. 
5. Good writing. I need to have just the good bones of writing. A nice balance between showing and telling. Authentic dialogue.Vivid descriptions. Fresh metaphors. Compelling chapter endings. The book should be great on the holistic level, the chapter level, and the sentence level. I'll be posting about Maureen Johnson's book soon, and she's a great example of brilliant writing at the sentence level. 

So there you have it. What would you add?