Def my favorite installment of the series so far. I loved the reveal about Nico di Angelo and he is now my favorite character in the Percy Jackson universe. 
 To be quite fair I wasn't too excited for Percy's and Annabeth's struggle in Tartarus but it turned out to have some interesting aspects. Percy going all mad for power and trying to kill Arachne with poision for example. 
 Hazel Lavesque is such a baddie and I love her magic tricks with the mist. 
 Still don't care about Jason or Piper... Sorrynotsorry