The Greek Gods are sometimes the Roman Gods instead (or too, whatever - it's kind of confusing to be a god), and their demigod kids are different from the Camp Half Blood people.
That is so not a spoiler. It's like the whole point of the book, and it's evident from early on. Yet, even though you kind of know where it's going, the book continues to dangle tantalizing hints in front of you, so you have to obsessively read and forego sleep to figure stuff out. By the end, a lot of things are made clear but questions are raised as well. Which is great. I love world-expansion. The author does it so, so well. I'm really looking forward to finding out more about the Romans in the next installment (also, I totally missed Percy), even though I'm pretty sure I like the Greeks better. Discipline and war - not into them. Also, you have to be brave and confident or you get eaten by a wolf? What if you're, like, a child of Aphrodite or Demeter - that doesn't really go with the nature of those deities. Anyway - I suppose I'll find out more about that in the next book. I'm hoping Camp Jupiter won't be like military school or something.
Jason was a little bland, but I think that was on purpose. He was a blank slate, after all, and he was loyal to his friends, which is always good. Leo was hilarious. "A Latino elf." Yep. Perfect description. And who wouldn't want a giant mechanical flying dragon? His story is really moving, even if he tries to deflect from it with humor. His character arc is great to watch.
Piper was a really great addition. We had Annabeth in the Percy Jackson series, and I love her, but she's not really emotional and feminine like Piper is. Which is fine - that's just not who she is. But I absolutely love how Piper shows that you can be very strong and not a "fighter" - that love is the most powerful motivator in the world. I've often noticed this, and yet it is generally overlooked and undervalued. She's just an awesome character. I've always hoped there was more to the Aphrodite cabin, and I always liked Silena.
It was really cool seeing Camp Half Blood from new perspectives and I was totally squealing over all the new cabins! I want to be in the Hecate cabin. So cool. I'm still eagerly awaiting a Goddess of Magic redemption. And of course in The Lost Hero we meet yet another sorceress who is evil. Come on, mythology! Aren't there any non-evil sorceresses!?
All in all, I am impressed.