Werewolves in Minnesota--hot young teen romance. That pretty much sums up the plot of these two books. There are also some themes of parenting (mostly bad parenting). This shows up as a well reviewed book on several review sites. I think it must be popular because of the romance themes.
Overall the book feels a bit derivative of the Twilight series by Stephanie Meyer. It has a little more description of romantic interactions that will appeal to romance readers.
Stiefvater has interests and songwriting, music, and art all of which appear as part of the book. And there were spots in the book where I think the writing could have used some improvement. I didn't always agree with Stiefvater's word choices.
Since I'm not much of a romance reader I don't think I will go on to read the third and final book in the series. I do have a mild interest in whether or not the main characters are able to find a cure for the werewolf virus. Unfortunately, I don't think I can get through all of the steamy romantic scenes to find out. I like to feel like I've learned something about the world as I read a book in addition to enjoying the plot, characters, settings and language. I didn't really feel like I came away with much from this book other than just entertainment.