I enjoyed this book a lot and I'm looking forward to the two sequels. It was recommended by a friend, whose daughter loves the series, and I can see why. It was fairly light and fun, mostly educational (it has a lot to do with Greek mythology), and very affirming of kids with ADHD and dyslexia.
You see, kids who are half-breed children of gods and mortals have trouble reading English because they're hard-wired to read and understand Ancient Greek, and ADHD because paying a little bit of attention to every tiny seemingly-irrelevant detail can keep them alive while battling monsters. [As an interesting side note, one of the things I've read on the listservs for Greek and Latin teachers is that dyslexic kids have an edge in learning those languages: kids without dyslexia have never had to pay such close attention to the letters ending a word before, whereas dyslexic kids have to do that all the time - it's a skill set they've already been forced to hone.]
There was one mythological inaccuracy that bothered me - one of the main characters is a daughter of Athena. Hello? Athena, the virgin goddess? Athena who is actualized with male characteristics, never actualized as a female according to ancient gender perspectives? [ETA: I mentioned this to my friend, who says this is at least partly addressed in a later book.] The author also repeats the old chestnut about Persephone being with her mom during the summer and in Hades in the winter (the blindingly-hot dry Greek summer is when the crops die and the land is bare - winter is part of the growing season in Greece).
OTOH, these quibbles out of the way, I hugely enjoyed a lot of the clever stuff that the author did with bringing the ancient Greek pantheon into modern times. The plot had some clever twists and turns. The hero was very likeable and Hermione Annabeth is a good strong female character of the type kids' books need to have more of.