I must confess that this middle book in the Percy Jackson series is not one of my favourites. I like it a lot as far as it fits into the world of the Percy Jackson series, however I don't like it as much as the previous two books. There are reasons for this which I will explain. That all said, the entire series is quality children's literature, among the finest in my opinion. They get kids reading and they get them learning about Greek mythology. I definitely think that's better than having them wanting a vampire boyfriend or to be a brutal all killing 'hero'.
The first two books in the series have a special kind of charm which appeals to me. The writing is not the best I've ever seen yet Riordan always excels in his banter and his characterisation. While not using overtly expressive prose he can describe a character succinctly enough to allow you to personally work out who they are. Much like how C.S. Lewis used succinct and yet elegant writing for his [b:The Chronicles of Narnia|11127|The Chronicles of Narnia|C.S. Lewis|http://d.gr-assets.com/books/1348864262s/11127.jpg|781271]. At the same time this can come across rushed and clumsy to the audience in particular places and I think that it happened here when I was re-reading this book. Perhaps I particularly noticed it because the book introduced some new characters and did not focus on Annabeth much at all. Annabeth is a pretty crucial character to the story I believe! Particularly since we see the 'quests' through Percy Jackson's perspective.
This is the book where the movement of this series begins to change and move toward the slightly darker climactic battle. This is where we begin to see the movement of monsters and titans. However I think that as a result Riordan fluctuates in tone and style from the previous two books. Perhaps I notice this because I have read the other books really recently but this book was less certain of itself than the others. By which I mean it was not settled in what it was addressing. It lost the charm of the other books and only the fun and ideas keep you liking it.
That said this is a good book. Its not the best book it could be since it's a kind of turning point, a place where Riordan resolves how he will settle about finishing the series. I still like it but it's not as good as the other books. Ultimately though I will always rest my case on the fact that it is always easy to be a critic and very hard to write a novel or work of imaginative fiction. Any proper author, whether I rate their book or not, always has my approval for their hard work in writing.