The story is rather linear and puzzles are without multiple means of solving in most cases. It makes the game seem heavily directed by design. Re-playability is also very limited in that you generally need to do the same thing every time, the only benefit of replay is to build up a relatively tiny amount of gold to teach your ghosts new powers to play with. It seems a very artificial way to extend game play. Replay doesn't allow you to bring ghosts earned in later level back into the early levels which further reduces the value of replaying.
That said, the concept is very creative and well implemented. The ghosts are fun and each an individual character complete with background. The mortals too have their own individual fears and backgrounds to prey upon. There is an abundance of character and story references to movies of the horror genre, usually in the form of puns, which make this game light hearted and fun.
So to summarize, it's fun and unique, more of a puzzle game than a strategy, but lacks replay value. Overall a fun game, but not a great value since it can be beaten in under 4 hours. Although for 6 bucks, I can't complain.