Seeing the usually totally incompetent characters of Yerzhanov trying to handle a hostage situation promises some stupid fun, and on that it delivers.

It delivers right from the start with the terrorist's entrance, just naturally walking into the school unnoticed while several people are just looking elsewhere (or totally ignoring them).

And during the heart of the movie, which is not really the actual assault, but the ridiculous preparation and training they go through. It's good. They're all as useless as you could hope. Except for Lena that turned out to be quite the sniper.

This is the actual movie, and it is pretty fun. However even if it was not the subject and could (should) be completely ignored, something was really annoying to me. The terrorists are really just a pretext to this "what if" situation.
We see them enter. They kill a kid at the beginning (just to show the viewers that they're really bad guys). And then that's it. We basically never see them again.

They never talk.
There's no reason behind their action.
They do not have demands.
They don't interact with the police.
Nor with Lena asking what they want.
Nor with the team ([spoiler]they barely even react when attacked[/spoiler])
Nor even with the hostages (nothing happens).
They don't even look out the windows ([spoiler]hard to miss the guys hidden between two sheep[/spoiler])
The teacher [spoiler]manages to do a full recon of the whole building, with pictures of them and everything, without getting caught/seen/heard[/spoiler].
The whole assault plan is based on the assumption that none of the terrorists will move an inch from where they were seen more than 24h before... and that's the case.

You could do the whole movie by replacing the terrorists by fruit baskets, and it would be exactly the same. It's so absurd, and feels like just an out of nowhere plot device to such an extent that what is missing leaves a much stronger impression than what actually is in the movie, and really diminish the enjoyment of watching it.