A few other people have already covered what I think, so this is basically a recap. I'd rate this one 2.5 if I could. I'll probably read one or two more to see if the series gets better (there are other series where I tend to skip the first book as being too bad/painful to read on a regular basis).
The positive: Interesting premise and urban-fantasy world, though the main character was slightly unbelievable (there were improvements as the book went on) and some of the situations were just plain weird. (Do you even *get* 8-inch heels?) The defining characteristics of the wolf packs was also interesting, but there was very little detail for a first book.
The negative: I really did not need to have the heroine doing the slutty dressing/naked and sex-all-the-time-with-everyone thing, which was constantly. Probably half the book was taken up with graphic descriptions of werewolf sex clubs and "matings". If I'd noticed those descriptions I wouldn't have read it in the first place.
I get that Arthur's trying to introduce something new for the werewolf "time of the month", but honestly... a full week each month where no werewolf does much of anything other than have random sex? And yet no-one really knew about them till recently? I don't particularly like books with so much completely casual sex and nudity, not to mention a few borderline rape scenes. Have the sex, but I don't need it to be quite so graphic *every time*.