The hands-down, best part of Everneath? The formatting. As boring as that sounds, let me explain, because it's actually really cool. Everneath starts after Nikki returns from the Underworld. Therefore, each chapter heading counts down how many days she has until she must go back. HOWEVER, the story is also told from before she went to the Everneath with the same countdown. This is a brilliant way to handle flashbacks and gives the reader a better insight into her character.
Another great part is that Cole's character isn't glorified. It is made very clear that any relationship he may have had/has with Nikki is abusive- he's manipulative, selfish, and dangerous. This doesn't mean that he lacks a sympathetic side- people are complex, after all- but his many negative behaviors aren't romanticized. His character has a lot of potential to develop throughout the rest of the series. Is he redeemable? We'll just have to wait and see!
Then there's Jack, and here is where I began to have troubles. Jack is agood guy, ultimately. It's easy to understand what Nikki sees in him and I love that they have a history of friendship (before their dating days). In fact, it's that history that allowed me to really believe in their commitment to each other. However, there are a few behaviors of Jack's that really bugged me, like when he pinned her to her locker in order to make her to talk to him, or grabbed her arm for the same purpose. Or when he told his friend that he didn't have Jack's permission to date Nikki three years before the book takes place. (Made worse by the fact that Jack was going out with, as Nikki puts it, "everybody" at this time, though apparently Nikki didn't have the same right.) This manhandling and possessiveness isn't okay- in fact, it's sexist behavior, plain and simple, from a character that the reader is supposed to find attractive and romantic. In the whole scheme of the book, these are small moments, but they are small moments that perpetuate negative standards.
On the upside, there is a great family dynamic. In fact, I wish there had been more, especially with her younger brother. But Nikki really cares about her father and he is trying to be a good parent in his way. Both Nikki and her father have to grow and throughout their difficulties, their love is evident. I loved that Ashton shows how the family is affected by all of the paranormal stuff that's going on, while they're still coping with the problems in their everyday lives.
Another positive? The mythology. Again, another aspect of which I wish there had been more. There isn't just Greek mythology, though of course Everneath centers around the Persephone tale, but there is a hint of Egyptian mythology, too. How Ashton combines the myth with secret societies and modern day is superb and I'm looking forward to seeing how this part of the story continues in Everbound.