Disappointing Ending

I agree, they didn't execute it well but the ending is not half bad. The killings were really just a red herring that sets up the misunderstandings between the main characters in the scene in the gym at the end. That is why they barely focus on the fact that it is the dean who murdered those girls at the end. Instead, the movie ending is more about trying to show that the visions instead of acting as a warning, brought about the bloody event itself (the death of the main character). As a result of the murders, Cassidy misconstrues from his visions that his friend Michael is going kill his sister and steals the gun, while Michael thinks the hustler Victor is trying to hurt her too, leading to the accident. This links back to Cassidy's mother not wanting the aunt to be around her children because she knew that the visions were dangerous because you get a skewed picture and the mother might have possibly even known that the aunt would lead her son to exploring these visions and lead to his death. I think one of the reasons the aunt screams at the end is that she realizes that by not listening to her sister's final wishes, she inadvertently helped kill her nephew by persuading him to have sex and see the vision. So really, the murders are just a setup for a fatalistic ending, where everyone from Cassidy, to the aunt, to Cassidy's mother bring about the foreseen event by trying to stop it.