Poor story concept: In a nutshell- Depressing girl moves to depressing town and falls in love with emotionless "vampire" and then is lusted after by a "werewolf", This book is a vain attempt for the writer to create an alternate reality where she is wanted by multiple guys in some fantasy she cooked up, likely the reason it appeals so much to the teenage female audience. The background story is flimsy at best, very little is explained, and mostly the entire story is filled with either romantic nonsense or Vampire combat.
The "Vampires" in this book are not Vampires, Vampires wake only at night, sleep during the day, lust for blood at any opportunity, immediately burst into flames when touched by Sunlight. The "Vampires" are also described as not having fangs. One of the quintessential features of a vampire is their fangs, needed to reach the deeper veins in the body where all the blood flows so they can feed. Now there is a degree of leeway with these types of things where one can still call something a Vampire, but in this situation it's like tying a party hat on your dog and calling it a Rhino.
The "Werewolves" are described as being able to transform into Wolves, at any time of the day, and when they want to, where as an actual Werewolf (Lycanthrope) only transforms during a full moon, has no say in the matter, becomes completely filled with a bloodlust when it occurs, as well as transforming into human-esque shaped beasts, with hunched backs, razor sharp claws and teeth, covered in fur and stand on their hind legs except when running. The "Werewolves" described in the twilight series should actually be considered Shapeshifters (Therianthrope) who choose wolves as their form.
/rant