October - "Toby" - has many reasons to be bitter, and few reasons to still have as much hope and desire for good as she does. Her ironic sense of humor is all the funnier when it twists around in the situation (and she ends up with a rose goblin named Spike), and her leaps of logic are easy to follow from within the first-person narrative ("Because you hate me."). Her background and current situation are painful and immediate in every little gesture, which McGuire manages to communicate without dwelling overmuch on the I- I- I- of every scene.
Once major challenge that McGuire had to overcome with the introduction of a "new" universe to a nearly jaded audience was how to educate newbies on many different types of sidhe and fairie forms without boring those who might already know. She accomplished that through creative use of dreams, third-character interactions, and magical interludes. A lot was still left up to the reader to decide if it was worth pursuing (who is Maeve, for example) because the background would provide depth but no change in meaning to the plot.
The biggest weakness to the book was that it had to cover so much back story that McGuire had to simplify some relationships too much. The who-done-it really wasn't a who nearly so much as a why, though McGuire tried for some misdirection using a couple of the secondary characters. She also killed off some secondary characters whose deaths weren't quite necessary, especially toward the end of the fight. The biggest strength to the book was its simplicity of presentation. McGuire did not aim for Epic! Worldbuilding! Fiction! She crafted and presented a character, a problem, help and harm, and pulled it all together nicely in the end. The ending was almost LKHamilton in its brevity (unfortunately), but can be excused as the first in a series. Tune in for the continuing story, to be released in two weeks.
If you are interested, here is an interview with Seanan McGuire.
ETA: Melebeth! you should check out McGuire's blog post about topics she is not allowed to discuss with reporters. here
ETA2: Ok, I could easily become a fan of her, rather than her work. Her official bio (on her web site) includes the following: She has strongly-held and oft-expressed beliefs about the origins of the Black Death, the X-Men, and the need for chainsaws in daily life.
ETA3: After prowling around on the internet, I went ahead and ordered two of her filk albums. They are very highly regarded by people who have heard of her.