
I recently read the entire Percy Jackson and the Olympians series, and tonight, I saw the movie. Here's my general review of the books. There will be a few minor spoilers, but nothing major.
If you like the Harry Potter series, I really think you would probably like these books, though they aren't quite as good. They are missing the epic struggle between good and evil that is the best thing about Harry Potter. When the major story arc involves conflict between the Olympian gods and between the Olympians and the Titans, there is no good and evil. The Greek gods are basically amoral, but the demigods and lesser mythological creatures do strive to be good. Even with that less than ideal attribute, I loved these books. Here's why:
1. They are full of Greek myths (and not just the biggies) wrapped up in a really cool modern package. Olympus, for instance, is above the Empire State Building. The Underworld is beneath L.A., and the Lotus Eaters are in a Las Vegas casino. You'll meet the Cyclopes, the Sirens, and the Fates, but they are all modern in their own special way.
2. They integration of Ancient Greece and modern America is super cool. Ever wonder what causes ADD and dyslexia? Find out in these books. (Hint: It has to do with battle senses and Ancient Greek.) How does a satyr who goes to a normal school hide his hooves? Wanna know why cab drivers in NYC drive so crazy? It is just so brilliant now well the myths are woven an essentially modern story.
3. One of the best features of the Harry Potter series that these books share is a fabulous group of main characters whose love for and devotion to each other are inspiring. The 4 main characters (one only appears later in the series) have different strengths and weaknesses that the group must leverage to succeed. Just like Harry, Hermione, and Ron.

The movie was okay. I'd say about as strong as the Harry Potter movies. They left out a lot of my favorite details and changed some things, but the adaptation was pretty true to the story and lots of fun. Who doesn't want to see Uma Thurman play Medusa? And The Parthenon in Nashville is in the movie, and we've been there, so that's cool. But read the books first.