Overall, this was a GREAT movie. I liked that it was in the perspective of the victims and not of the shooter him/herself. I didn't really think that any of the acting was cringy, and I thought that this movie did a really good job of containing dialogue that high school kids would actually say.
That being said, the ONLY thing I have a huge complaint about would be that it took the staff SO LONG to notice that there was an active shooting. There would at least be a few staff members on duty, especially on senior prank day. I think that was a bit too much reality for me to suspend.
I think they did a great job combining several facets of past school shootings.