Violence and theme-wise, this is the most adult UF-like YA series I've come across. There is no sex, and very little cursing. It is gritty, though, and I think shows a lot more of what the reality of fighting for your life day in and day out would do to you. 
 Billi SanGreal is a knight, one of the Templars who fight for humanity against vampires, werewolves, demons, the occasional fallen angel and gods. There are religious overtones - the Templars are fighting for God, and vampires sell their souls to the devil for immortality, but it's not preachy. There is no time for preaching. This war isn't without sacrifices, too, something Billi knows very well. 
 There is so much tension in this series for me, especially after events in book 1. I didn't feel like anyone was safe at any time. 
 At the same time, it wasn't as though everything was hopeless. It's dark, yes, but I was still cheering Billi on. The book flowed really well, and while I might have liked to get to know some of the side characters better, I'm glad that there are threads left for future books. Will be looking for more from Chadda.