I originally said it was 3.5 stars, but after letting it marinate I'm bumping it up to a solid 4 stars. For some reason I didn't think this was YA when I started it, so I wasn't really prepared for Cas. At first he sort of annoyed me, but that's sort of the point; he grows on you as he makes friends in his new home and starts to question why he does what he does and how it should be done. At the end of it, I like Cas and his friends and will definitely read the sequel (it seems like there is going to be one). The only element I didn't really like was (view spoiler)[that the kids so easily played off the murder of their friends by ghosts and didn't really see what Mike did to Cas as a big deal. They're teenagers - there would definitely have been more drama, but at the same time, I'm sort of glad to not have had to read it. 
 It was cute that Cas spent time with Anna and in the end he fell in love with her. (hide spoiler)] 
 I'm not really sure where the sequel would go (view spoiler)[aside from trying to bring Anna back from wherever she dragged the bad ghost (hide spoiler)], but I'm interested to read it.