I would have given this movie 7 or maybe even 8 stars if not for one HUGE inconsistency in the movie: The characters who end up being the killers are completely inconsistent between the 1st and 2nd halves of the movie. For example, they have multiple "secret" conversations with just the two of them trying to "figure out" if one of the other couples could possibly be the murderers. They make comments such as "It really could be them", and imply that they really think a specific couple is the murderers. This is completely inconsistent because if they were alone (and they were the murderers all along) then why would they feel the need to speak like this to each other all by themselves???? It does not reconcile. The only reason was to "trick" (or basically, lie) to the audience by making them completely different characters half-way through the movie, and ignoring everything they might have lead us to believe about them up to that point, whether it makes sense or not. I love a good plot twist, but when the writer/director has to lie and make the characters inconsistent like this in order to do so, it really turns me off of the movie.

Other than the above, the scenery was unbelievable and makes me want to go to Hawaii very badly, and I thought the acting was terrific.