On the plus side, it's very clear Riordan heard the reviews of people saying Percy was too dumb in The Heroes of Olympus. Every opportunity he gets, he makes sure to mention that Percy "isn't as dumb as he seems". Also, this was... well... better than [b:The Lost Hero|7736182|The Lost Hero (The Heroes of Olympus, #1)|Rick Riordan|https://d.gr-assets.com/books/1277091656s/7736182.jpg|10107891]. But then, maybe it was because the said book lowered my expectations for this one.
There were also many things I liked about the concept of the novel, with Camp Jupiter and everything. But everything was so rushed through... It feels unpolished. Camp Half-Blood was a very well done congregation of adolescents, with some being more forceful than others, but all of them just worried about getting on with their lives. Camp Jupiter is a nice idea, but it's executed as a collection of bullies. Riordan doesn't take the trouble to add color to any secondary camp inhabitant, he does just enough to make sure you understand that Percy and his friends are underdogs who get picked on all the time and it's SOOOOO UNFFAAAAAAIIIRRRRR!!!!! *eye roll*
In the previous books, I have mentioned how much I hate unnecessary romance and romantic triangles. This book almost made me retch in this category. I have honestly lost count of how many love triangles he has created for this series. What, having demigods, Classical gods and mythological monsters walking around is not enough? You have to force the poor characters to suck each other's faces, and angst about other characters sucking each other's faces?
The whole book feels unpolished and rushed. There is such a build-up and so much stress about some things at the beginning, and when you get to the end they're just mentioned in one phrase and solved with a wave of a hand. It feels like a first draft: the plot itself is solid, but the details need a lot
Finally, I mentioned this in my review of [b:The Lost Hero|7736182|The Lost Hero (The Heroes of Olympus, #1)|Rick Riordan|https://d.gr-assets.com/books/1277091656s/7736182.jpg|10107891], but it bears repeating: it would be so much cooler if he had included other religions in this. He even had the perfect opportunity for it! When Frank and Hazel are fighting against Alcyoneus, he could have included some Inuit god. He had even mentioned Inuit gods earlier, saying that they were ravens and bears. And, you know, even when you take Alcyoneus out of "his homeland", he's still a giant, right? So he could only be killed by a demigod and a god working together. Nobody said it has to be a Roman or Greek god. If he had just put, I don't know, a raven flying low and pecking out the giant's eye while Frank struck the killing blow, not only the plot hole would be eliminated, but the story's universe would have been expanded tenfold, just like that. He didn't have to keep including other religions, maybe they're all ignoring the demigods, but that would give him the possibility to use them. And the series would have been that much richer for it.
Again, sure, the writer has the right to write the story he wants, but I hate to see such a golden opportunity being missed.
At this point, I'll keep reading the series just because it makes me feel better about my own writing.