Broken Base: Some praised the filming of the shooting for its stark realism and nightmarish setup, while others criticized the wooden acting from the cast (which was comprised of many non-actors) and found the reactions of the students completely unrealistic, as many fail to react at all to the sight of students with guns or, in Benny's case, dead bodies and fire.
Complete Monster: In this film based on the Columbine shooting, Alex is a cold-blooded rampage killer who attempts to massacre his entire school. Alex, along with his partner Eric, plan to bomb the school and gun down the survivors, which would've killed hundreds of people. When the bombs fail to go off, Alex and Eric settle for going room to room and shooting everyone they come across indiscriminately. When Alex and Eric regroup in the cafeteria, Alex kills Eric in cold blood, and proceeds to play a sadistic game of "Eeny, meeny, miny, moe" with a couple that had been hiding in the freezer. While Alex, along with his fellow shooter Eric, had been bullied by his classmates, Alex's actions appear to be motivated by little more than the desire to hurt others for fun.
Fridge Brilliance: When Alex and Eric are making the last minute preparations for their killing spree, Alex takes the lions share of the weapons (an assault rifle, combat shotgun, and several pistols), leaving Eric with only the Tec-9 and a handful of knives to use as a weapon, giving Alex a clear and unfair advantage in armaments. This is intentional on Alex's part - in the end scene, Alex kills Eric without a second thought. Alex was making sure Eric would be as underequipped as possible in an armed confrontation.
Harsher in Hindsight: While it's obviously hard to watch after any high profile school shooting, the Red Lake shooting of 2005 (as gunman Jeff Wiese saw the movie a few weeks before the tragedy) and the Umpqua Community College shooting of 2015 (which also happened to take place in Oregon, the state the movie was filmed in) are especially unsettling given their context.
Nightmare Fuel: For obvious reasons, the shooting itself. Alex and Eric go from room to room and shoot people to death in a more realistic manner than most movies. Alex suddenly killing Eric and playing a sadistic game of "Eenie meenie minie moe" with a couple of survivors stand out in particular.
The Woobie: Many of the characters, but one that stands out the most is Michelle. The films shows her as this shy, insecure young girl who covers her body in the gym, wears the same khakis and red blouse, and mainly volunteers in the library. She doesn't have much going for her and she barely gets a word in edgewise before she gets shot.