The characters were interesting enough, but I would have appreciated a little more time with them. It seemed like there were too many boys in the gang to get an opportunity to learn about any one of them. Stephen was a self proclaimed boring guy and I didn't have the strength of feeling for him that I had hoped. I was a big fan of his bitter and cruel grandmother - at least she kept things interesting.
The plot of The Cemetery Boys didn't quite go the typical route. There were some events that were pretty predictable, but one or two plot twists that I didn't see coming. It was fast paced enough to keep me connected to the plot while still allowing for an air of mystery.
There was one particularly large issue (though I don't know how much power an author has over this, it may be a publishing decision): I hate prologues that consist of an insert of a scene from later in the book. In some books, the prologue is an integral part of the plot, in others it acts as some type of teaser for the most exciting part of the book. In this case, it was the latter. It featured a seriously important scene which gave away a large part of the story. Reading it ruined the flow for me as I just kept waiting for that scene to happen. If you have this one on the TBR pile, do yourself a favor and skip the prologue.