My full review is here on my personal website. I'll post a few excerpts here, though:

4.5 out of 5.0 stars

The very worst thing about this book is that Percy is starting to come across as a masochist. “Oh, I have to make this right. There are others who could potentially fix these problems, or at the very least help me, but it has to be me to do it.” Maybe this is because I read the books one right after another, but whatever. It didn’t detract from the book. After all, if he wasn’t willing to shoulder the burden, we wouldn’t have the hero. ^_^

The very best thing about this book is still the elements of mythology. I really, really, really like that! Even if I liked nothing else about the books, that aspect would keep me reading them. I love the idea of mythological beings and creatures still existing and having a hand in the world today. :-D