This was a fun, fast book to read. The book is only 14 chapters, although I felt it could have been a little more to it. We don't get a lot of backstory on Mary, or Rachel, so I didn't really care about the characters as deeply as I could have. Another character who could have used more development was Mary's grandmother, or Gran. Gran is a fortune teller and the reader doesn't quite have a clear picture of what she looks like, or even how the house they live in is set up.
I would have liked a little more descriptions of several things, since after reading it (and I only finished about 3 hours ago) I can't remember what any of the characters look like. None of them really stuck with me, and I would have liked a little more from the teens who were terrible to Mary. There were more than a few, but the only name I remember is Vicki, and again, I can't quite picture what she looked like.
Now, just because I didn't care for the lack of description, and character development, does not mean that I didn't like this book. I thought the idea behind it was interesting, and found it delightful that Mary had a characteristic that I hadn't seen in a lot of other books, being able to hear but not see the dead. In the end, I thought the most delightful character was Chowder, a ghost dog who comes and goes into Mary's life. And to be honest I can remember more about him than any of the other characters (seriously, what color hair did Rachel have? I want to say red... Maybe).
I may or may not read the next book in this series. I have to think about it, and maybe get through a few more novels on my TBR shelf before buying anything new.