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 Rachel Dare. For some reason, I just don’t like her. Personal reasons that go back to other girls flirting with my boyfriends and that sort of thing. She just seems like the type who wouldn’t mind if Percy was cheating on Annabeth as long as he was smooching her, too. As a character, she’s fine; as a person, I would have serious issues tolerating her. Also, if this sounds petty, it’s because it is. The books are great. ^_^

The very best thing about this book is the Labyrinth! I’ve always been a fan of labyrinths, and having this book’s main points centered around the Labyrinth is a huge plus for me. ^_^