I appreciate this book for what it is. At its time of publication, the "young adult" novel was still in its infancy and there weren't many books in the genre willing to explore important subjects. Anderson was one of the first young adult authors to understand her audience and come up with something with literary value they'd actually want to read.
I'm not going to write an in-depth review because there are a ton of reviews for it on this site already. The prose is on occasion surprisingly funny, and the main character is believable without being likable. I feel like my enjoyment of this novel was hampered by the fact that I had read some truly awful imitations of it before I got around to it, and couldn't quite get those out of my mind as I read. But while I didn't particularly enjoy reading this, I don't feel like I completely wasted my time either.
I will say that after working through most of the canon of Ms Anderson, I found "Wintergirls" to be the best thing that she has written.