Josie and Fox make a terrific brother-sister team. Not only do they work the auction house well and are helpful to their family, but they also do a fantastic job at figuring out the Mothman curse and dealing with it in an effective manner. Fox starts off the book as kind of a goof, but manages to become more serious, and Josie goes from being a fearful shadow of her brother to being the kind of girl who is willing to sacrifice herself if that is the only recourse. Their mother is dead, which was an unnecessary bit of sadness, but they are handling their grief well. The other adults in their lives are supportive and helpful.
The use of local legend, landmarks and lore works very well and makes for a story that is much creepier than the cartoonish cover would indicate. Like the southeastern Ohio setting in Black's Doll Bones, this view of Athens is a bit gritty and macabre, but never devolves into "hillbilly" stereotypes. The descriptions of place don't weigh the book down at all, but are deftly worked into a plot that is well paced and which has its share of action and suspense.
A haunted Polaroid has been used before, in the Scholastic Poison Apple Now You See Me, but this works, too! I was glad that the camera in Mothman's Curse didn't require film!