I was impressed with the quality of writing, just as I expected to be. Gaiman captures the mood perfectly - it starts off innocent and child-like and quickly becomes dark and sinister. The protagonists are all well developed and interesting, especially Lettie. I also think Gaiman does a great job of combining the fantasy elements of his story with the real world. His magic system is intricate, but he doesn't waste too much time describing exactly how things work.
While I really appreciated the quality of writing, I was less impressed by the entertainment value. It took me quite a while to really get into the story and then I lost interest again before it was over. It's not that the story wasn't well-developed and I liked the protagonists, but the antagonists just did nothing for me. I was mostly just confused and wanted more development in terms of explanation for motivation for the antagonists.
That said, I did enjoy the middle of the story and experienced some of the deliciously creepy moments I was hoping for - just not as many as I had expected.
I'm not sure this is the best Gaiman to start with. My friends who are friends are all raving over it, but I've heard responses similar to mine from those who aren't familiar with him as an author. It's great in terms of writing, but I just wasn't as excited about it as I had hoped. I'll definitely read the author again, based on the quality of writing.
Thanks to William Morrow for providing me with a copy of this book to review!