The characters act the same as they did in the movie, and I'm grateful for that. The universe in this case is about the gods of Olympus and their sons in the most original way. There are special gold coins, and gods out there that perform their own business for America, like Medusa being the only mother of a stone Garden Emporium. Percy is not just a demigod: he's a dyslexic only son of the ruler of 85% of the entire earth. The same rescue mission from the movie ensues, finding Percy's innocent mom and informing Hades he never took Zeus' lightning bolt.
It was a non-stop thrill ride I wish I could have joined alongside them. Grover is the same goat, but hates how we have polluted the world so much you can't really see the stars anymore. Annabeth can be forgiving of mistakes, but a bit gloomy. A kind of unpretentious optimist. In this version, the gang goes off hoping clues to the next place will pop up. Most of the action scenes, which there are several of, express it as good as a movie would. When I write an action story, I try my best to foreshadow a battle, but to add mystery of the foreshadowing to it, such as when Percy is given a warning about not accepting gifts, and that he'll fail to accomplish something. It's like The Rig by Joe Ducie. In that book, from Chapter 1, you know Will Drake will escape, or at least try to, but we have no idea what's going to happen. Unlike most dismal popular books, this start to the series will give you satsfaction before whatever activity you're about to do, it getting as imaginative as rocket science a few times.