The bad thing about being a learner of writing and filmmaking is that you'll find your "critic" persona taking over more often than usual whenever you are watching a film or reading a book. It's like Brecht's distancing theory of the audience where instead of investing emotions into the characters and feeling for them, you take a distanced viewpoint to deconstruct analyze the plot scene by scene; By being critical, you don't quite get the emotional catharsis found at the climatic moment of the plot.But when it comes to shows like Harper's Island (a la I Know What You Did Last Summer in episodic form) where part of the fun is guessing who is going to die in each episode, it practically encourages you to do so - there isn't much motivation to bind with the characters when you know most of them will be cannon fodder at the end of the show.
Despite suffering from the usual stuff associated with slasher films (characters doing stupid things alone, tons of red herrings to mask the weakness of plot) it's still enjoyable in a brainless kinda way. That is if you have extra time to spare.
Three guesses about the eventual killer:
(1) Killer is none other than the main character (Abby) - We all know about the unreliable narrator from films like The Usual Suspects and Memento.
(2) There is more than one killer - I remember feeling absolutely shocked when I saw the twist of Scream when I was 12. Nowadays it's a pretty often used plot device.
(3) The killer is one of the seemingly killed characters - I dislike using this device as it purposely misguides the audience and doesn't give any allowance for them to guess at all. Can be worked together with (2).