This is one of those books, and series, that is well-written, with pretty good plotting and very well-crafted characters, but just fails to engage me. I've been reading these books since the beginning and I've never not enjoyed each one, but they've never resonated enough with me that I've been eager to pick up the next one. I feel bad about this because it is a good series, but if I'm not looking forward to the next release, I need to just let it go.
It's definitely a case of "it's me, not the book" so if you enjoy light, totally non-spooky ghost stories tied to good mysteries and written with a lot of humor, I'd definitely recommend giving this series a shot, it deserves it. I'm going to hang on to the books I have, just in case, but I'll probably end with this one.