There will be a lot fo people who love this novel simply because they love angels and demons, love triangles, and good girls who catch the attention of the bad boy. Unfortunately, for readers who enjoy strong plots and in-depth characters, they won't get it here.
The first "sore-thumb" that stuck out in this novel was that the author tried to write it from two different points-of-view - Luc and Frannie. Other reviewers have commented on this, and I agree that it wasn't executed well at all. In fact, Luc sounded like a cliche, sex-driven teenager instead of a 7,000 year old demon from hell. In addition, his voice was so similar to Frannie's that I had to look at the title of the chapter to remember who was talking. Not only that, but Gabe was "supposed" to be an integral part of the love triangle, but the reader never read his POV, which left him out on the fringe. Instead of doing the alternating POVs, the author should have taken an omniscient voice to make the reading more fluid and believable.
Now, the love triangle. It was simply contrived. I mean, it's not like I didn't see it coming, but it was so poorly done that I honestly didn't care. For instance, one minute Frannie is wanting to have sex with Luc, then out of nowhere she fantasizes about Gabe. In fact, Gabe disappeares for chapters at a time, then all of a sudden, Frannie gets mad at Luc, and runs to Gabe for "comfort" and wonders if she's in love with him. In the real world, this is called a rebound. Also, I never felt like Frannie was in love with either of them with how easily she flip-flopped. Instead, it just seemed that she wanted to have sex and was willing to be with whichever showed the most interest.
Now, Frannie. She claims to be a strong female and doesn't need a male in her life to feel self worth; yet, within a few chapters, she's obsessing about Luc, Ryan, and Gabe. A little contradiction? In fact, her goal becomes getting the two "hottest" guys on campus interested in her before her best friend, who seems like a nymphomaniac, can.
Now, the language. This may seem minor, and, in fact, I'm pretty liberal with my views on curse words when they're used in the proper context. But, the characters used so much language in this book that it came off like they were trying to "play like adults" instead of representing high school seniors. When I teach a young adult novel, I'm very straightforward when I tell my students that language is part of character development, and it adds to the authenticity of the novel. For instance, if we're reading about inmates on deathrow, we aren't going to see them say, "Brother John, let us break bread together." No, they are going to use the "F" word as well as a few others that aren't so PC. But, even then, the author has to choose the language and decide what adds and takes away from the novel. This one relied too much on puns like "Go to hell" to the point that I was rolling my eyes.
I have other frustrations, but, overall, I wouldn't suggest this one.