I am a huge PJ fan and have been eagerly anticipating this last installment ever since I finished The House of Hades. However this is my least favorite book of the series and I am a little disappointed. (Spoiler Alert- I will be channeling my inner River Song and there will be lots of spoilers!)
Pros- I really enjoyed learning about Reyna more in this book. Up until now, we knew very little about her. She has quickly become one of my favorites.
This is well written in the usual Riordan style which sucks you in to a world full demigods, monsters, and prophecies. I read this entire book in less than a day! Only two other authors can capture me like Rick, J.K. Rowling and J.R.R. Tolkein.
There was plenty of action. I read this entire book in less than a day! The pages practically flew as I followed the seven, Reyna, and Nico on their adventures. Riordan kept the plot fairly fresh and didn't just copy TLO. Hazel, Frank,Piper,Leo,Jason,Reyna, and Nico were all developed more and it was told in their POV. (But that also leads me to one of my biggest complaints)
Cons- Percy and Annabeth were almost entirely forgotten. The story was never told in their POV which bothered me throughout the whole book. They were the ones who we met first, so I had hoped that they would be the ones who were fairly prominent in the end, or at least present. The really seemed like filler characters which was a huge disappointment. Also, their time in Tartarus seemed to make them weaker instead of stronger, which does not fit at all with their character.
Gaea was way to easy to defeat. With all the hype that was placed on how powerful she was, it took three teenage demigods to defeat her. Why even have the seven if it's only going to be Jason ,Piper, and Leo? I had expected that it would take all seven to put her back to sleep. And Piper's charmspeak seemed a tad to powerful if she could all of sudden put the worst goddess to sleep just by saying "SLEEP".
There was no cost of war. TLO was so amazing that I was expecting something like it. There were real losses, Beckendorf, Silena, and Luke, but they didn't seem like it was just for sentimental value. Their deaths had meaning. None of the seven even got majorly injured! (Minus Jason's sword through his stomach, which he managed to survive) Even when Leo was going to "die", we knew he had a way out and that he wouldn't stay dead.
Overall BoO was okay, but I still feel a little disappointed that it wasn't even close to my high hopes. I would still recommend this to any PJ fan though!