Is Elephant a better film? That can be debated but all I know is that this was 10 times more effective to me than Elephant. It's definitely one of the best found footage style films. The surveillance sequence was incredibly realistic. It isn't perfect...I could've done without the ending. I get what they were going for but it would've been more effective had it ended at the end of the surveillance tape.
This is one of the great underrated films of the last decade, in my opinion. As a study of school shootings it wipes the floor with Elephant (well the scenes focusing on the shooters at least). Here we are presented with two completely believable and complex characters and the found footage technique creates an amazing level of intimacy between us and them. The performances, script and direction are all astonishing.