3.5 Stars 
 For fans of light urban fantasy, this book has a number of tried and true aspects to offer--all wrapped in an upbeat and adventurous package that should strongly appeal to the 9-12 age range. 
 The unseen world-within-a-world premise strikes a familiar chord--particularly in centering on the main character single-perspective of Percy, who discovers he has blood-born preternatural abilities and is sent to a hidden summer camp filled with other teens and pre-teens much like him. Those familiar with the Greek pantheon will quickly get a handle on the world-building, and those unfamiliar will get a steady-yet subtle lesson in Greek mythology. 
 This demi-god coming-of-age tale is a rollicking good time, fraught with classical monsters and adolescent derring-do. Slow on the pickup and sporting a unique blend of sarcasm, ADHD, and dyslexia, Percy makes for a refreshingly flawed protagonist. The writing style is simple without talking down to its audience and obvious moral quandaries are addressed without a needlessly instructive tone. 
 On the downside, Percy's mother came across as pretty one-dimensional. She was so perfectly sweet, kind, patent, hard-working, understanding, protective, self-sacrificing, long-suffering... she just didn't feel like a "real" person. It was a bit difficult to care much about her fate--though it was clearly meant to be a primary motivating factor for Percy. Annabeth also seemed to lack some depth, but to a much lesser extent--and her character growth made up for much of this toward the end. 
 One particular concern gave this reader maternal pause, coming in the form of Percy's dislike for Tom Sawyer. While his dyslexia is certainly cause for literature anxiety, he seems to spin it as an excuse for copying an online book report rather than suffer having to read it. (Sadly, no mention made of the audiobook option.) I can only hope Riordan wasn't purposefully trying to put anyone off on classic literature.