I liked the first book of this series a lot, and The Sea of Monsters was a nice follow-up. But The Titan's Curse was not nearly as good as the first two. Much like Order of the Phoenix, in the HP series, we find out some interesting bits to the overarching story in this book, but the pacing and much of the plot just felt off to me.
Riordan relies way to much of "future reveals" as in, "Annabeth looked directly at me. 'Percy, I should probably tell you something.' But our conversation was cut off by Grover who stumbled into the room out of breath." Exchanges like this happen all throughout the book. The info is withheld from the reader, sometimes not revealed at all, sometimes used later for a climactic end to a chapter. I began to find it really annoying.
Another thing that is starting to bug me is that no one ever dies. Percy and his friends are constantly fighting all sorts of monsters and (new as of this book) Titans, but no one is ever killed. Even when is seems like someone has died, you find out twenty pages later that they are not dead. And in most cases, Riordan does not explain how they managed not to die. That was one of the aspects of the HP series that I really liked. When people faced down real danger, they didn't always make it through.
There were still many positives to The Titan's Curse. The plot of the series really begins to unfold in this book. Riordan continues to deftly weave together Greek mythology and the modern world, in ways that are unique and often funny. In the case of Riordan v. Rowling, I side with Rowling on nearly every issue. However, when it comes to humor, Riordan has a slight advantage.
My review of The Lightning Thief (Book One)
My review of The Sea of Monsters (Book Two)