here was no effort put into Valentine to prevent it from being just another teenage slasher film, a sub-genre of horror films of which we have seen entirely too many over the last decade or so. I've heard a lot of people complaining that the film rips off several previous horror movies, including everything from Halloween to Prom Night to Carrie, and as much as I hate to be redundant, the rip off is so blatant that it is impossible not to say anything. The punch bowl over poor Jeremy's head early in the film is so obviously taken from Carrie that they may as well have just said it right in the movie (`Hey everyone, this is the director, and the following is my Carrie-rip-off scene. Enjoy!'). But that's just a suggestion.
(spoilers) The film is structured piece by piece exactly the same way that every other goofy teen thriller is structured. We get to know some girl briefly at the beginning, she gets killed, people wonder in the old oh-but-that-stuff-only-happens-to-other-people tone, and then THEY start to get killed. The problem here is that the director and the writers clearly and honestly want to keep the film mysterious and suspenseful, but they have no idea how to do it. Take Jason, for example. Here is this hopelessly arrogant guy who is so full of himself and bad with women that he divides the check on a date according to what each person had, and as one of the first characters seen in the film after the brief history lesson about how bad poor Jeremy was treated, he is assumed to carry some significance. Besides that, and more importantly, he has the same initials as the little boy that all the girls terrorized in sixth grade, and the same initials that are signed at the bottom of all of those vicious Valentine's Day cards.
It is not uncommon for the audience to be deliberately and sometimes successfully misled by the behavior of one or more characters that appear to be prime suspects, and Jason is a perfect example of the effort, but not such a good example of a successful effort. Sure, I thought for a while that he might very well be the killer, but that's not the point. We know from early on that he is terrible with women, which links him to the little boy at the beginning of the film, but then in the middle of the film, he appears at a party, smiles flirtatiously at two of the main girls, and then gives them a hateful look and walks away, disappearing from the party and from the movie with no explanation. We already know he is a cardboard character, but his role in the film was so poorly thought out that they just took him out altogether when they were done with him.
On the positive side, the killer's true identity was, in fact, made difficult to predict in at least one subtle way which was also, unfortunately, yet another rip-off. Early in the film, when Shelley stabs the killer in the leg with his own scalpel, he makes no sound, suggesting that the killer might be a female staying silent to prevent revealing herself as a female, rather than a male as everyone suspects. But then for the rest of the film, we just have this stolid, relentless, unstoppable killer with the emotionless mask and that gigantic butcher knife. Director Jamie Blanks (who, with all due respect, looks like he had some trouble with the girls himself in the sixth grade) mentions being influenced by Halloween. This is, of course, completely unnecessary, because it's so obvious from how badly he plagiarizes the film. The only difference between the killer in Valentine and Michael Meyer's is that Michael's mask was so much more effective and he didn't have a problem with nosebleeds. This stuff is shameless.
At the end, there is a brief attempt to mislead us one more time as to who the killer is (complete with slow and drawn out `and-the-killer-is' mask removal), but then we see Adam's nose start to bleed as he holds Kate, his often reluctant girlfriend, and we know that he's been the killer all along. Nothing in the film hinted that he might be the killer until the final act, and these unexplained nosebleeds were not exactly the cleverest way to identify the true killer at the end of the film. Valentine is not scary (I watched it in an empty house by myself after midnight, and I have been afraid of the dark for as long as I can remember, and even I wasn't scared), and the characters might be possible to care about if it weren't so obvious that they were just going to die. I remember being impressed by the theatrical previews (although the film was in and out of the theater's faster than Battlefield Earth), but the end result is the same old thing.

Sentiment: NEGATIVE