The characters are all great. I do think a few fell just a little into the "I'm just here for plot reasons", but only a few. Most of the side characters were actually very flushed out in my opinion. Our main character Isobel is very well rounded and I loved her. I also like that it showed that not all cheerleaders are bitchy. One of my best friends was a cheerleader and she was so sweet and awesome (most of her friends were your typical cheerleader type but she wasn't.) I like that Isobel wasn't scared to stand up for herself. She did what she thought was right, even if it meant losing her friends. I love people like that.
Varen... I have a soft spot for any alternative person. I usually fall for them in any book they are in. Varen was no different. I fell for him right along with Isobel. He's so perfectly dark and such a lonely soul. I can see why he did the things he did and I can't fault him. I understand him.
The plot is top notch, it does take a while to get started but I'm glad for that, it gives you time to get the characters set up and the feelings between the two to start. I can't wait to dive into the next one which I recently got.