** spoiler alert ** 
 I think I really like Lester more than Apollo. He's still a bit of a narcissistic ass, but he's slowly learning about humanity and to act more human. He's much less annoying as a human than he was as a god in the other Greek/Roman novels. Being human has also made him reflect and think about his behaviour as a god, and he is willing to admit he sucked (not too much, but he's starting to see he was a jerk). Also, the parallels between Apollo and Meg when they were facing off against Nero before the Grove of Dodona. Very interesting. 
 Speaking of which, I want to know more/see more of Meg. I'm very interested in her back story with Nero, who I was surprised and happy to see as the big bad. Not so much surprised that he was the villain, but what Riordan has done to create Nero into a villain and explains how and why he's amassed such great power. The whole concept of turning yourself literally into a god is something really interesting. I can't wait to see where that goes. I'm hoping the other two emperors are Tiberius and Caligula, although making Emperor Little Boots kid-friendly is a Herculean task. Maybe some Game of Thrones jokes about the Lannisters? 
 I like the fact that most of the PJatO/HoO characters are pretty much peripheral, and not front and centre, although Leo's going to be a main character in the next novel, along with Calypso! I guess this is pretty close to my "write a whole damn series just on Leo and Calypso having adventures because it will be awesome!" wish. The fact Calypso and Apollo are now both mortal and powerless should be full of fun times. 
 With the exception of the Kane Chronicles (which are still good, don't get me wrong!) I honestly find Riordan's writing improves with each series after Percy Jackson and the Olympians. The prose is tighter, and the characters are also becoming much more diverse and interesting. 
 Also, one final thought, I adore the Will/Nico romance. The doctor's note to be able to sit at the Apollo table was really cute. I love that Nico's finally getting some happiness in his life for a change.