I cannot say enough how much I love a male POV in a YA book. It's not done nearly enough. Cas is amazing. I love that he feels for Anna, that he's brave but not too brave. I love the he's slightly reckless and that he cares enough to always want to protect his friends. I love his occasional outbursts and that he's sometimes selfish. 
 It's kind of like a quest for Cas. There are adventures and traveling and general (scary) awesomeness. 
 Thomas and Carmel are awesome. I love that Thomas will do anything for Cas and Carmel is always a bit afraid. They are the perfect sidekicks for Cas. 
 You get to meet the mysterious Gideon, and he turned out to be such a fascinating character. There's a few new characters as well, but they weren't as cool as Gideon. 
 Girl of Nightmares is one creepy, scary book. There is one scene in the book that I cannot get out of my head. I'm surprised that I didn't have nightmares for real. (Note to scaredy cats like me: read this book in the daylight!) 
 Girl of nightmares is so much more than Anna Dressed in Blood. More of what I cannot tell you, just know that there is more. And you will like it.