There are SPOILERS for the previous book in the series along with this one. Read at your own risk.
So I've finished the series.
And now I'm going to be very nitpicky because while it was one of Rick Riordan's finest works, it did have some things that bother as big a fan as I (and things that I know bothered other fans).
Let me start with what I loved. The characters. Especially Leo, who gets the best ending ever. At this point I'm pretty sure that the series revolves around him because he's definitely the hero of this book. I say, more Leo! And more Coach Hedge, who is the funniest character I've read in a long time. So long, I can't think of anyone else nearly as funny. Nico and Reyna were surprises, and I ended up caring much more for them than I thought I would at the beginning of the book.
I also loved the last third of this book. I couldn't put it down, it kept me out of breath and on my toes, and had my crying, laughing, and experiencing everything alongside the characters. When a book does that to me I can't help but give it five stars.
One thing I know bothered a lot of people was the lack of Percy and Annabeth. I mean, I didn't really mind it that much. From a creative stand point I think it was a poor decision to axe their POV, but I've had quite a bit of issue with the way he organized this series, chapter-wise. I'd love to rant about it, but I feel like no one wants to hear it. If I'm wrong, let me know in the comments.
I, personally, found the first two thirds hard to get through because it was the same thing I had read in the first four books. Basic formula of 1)Demigod lands and stumbles into trouble with local deity/mythological creature, 2)Demigod talks/fights way out of mess learning a valuable lesson or gaining a valuable item, 3)Demigod learns from mistake and takes off again, rinse and repeat. Basically, it became rote and boring. I didn't think it was necessary for this book, either, since so much was happening already. It almost felt like Riordan just needed to fill up the pages and was running out of plot. Something else that added to this feeling was the more and more obscure characters he was pulling out of mythology. For the most part, that was fine with me, but I just found myself getting lost in some really complicated names and trying to remember everyone by the end.
The biggest issues I had were that Percy's family was pretty much completely left out (and not just in this book, but the whole series) when they were a big part of the prior series. There's a few references, but nothing concrete and even just a small appearance would have added so much. The other big issue is that it all felt unresolved in the end. While the major plot is completely done and tied with a nice bow, there were many unfinished plot lines that make me think he's planning another spin-off of sorts. For example, Hazel and Frank were just kind of left without answers to their problems.
Overall, I really did love this book. Looking forward to whatever he writes next. To add it on goodreads, click here.