Note: spoilers!
I found it very dissatisfying, as all the way through the "thought experiments", completely illogical and unrealistic things occurred, which just made me disengage. The premise of the experiments was using logic over emotion, but the situations themselves were ridiculous. Examples:
No bunker meant to preserve human life would allow the occupants to die just because, after a year of trying to remain sane, someone forgot or misplaced the exit code. Ridiculous! The lock would at least be timed, with a fail-safe to open if oxygen inside is low, and/or as soon as the air outside is safe.
The teacher spitefully screws them the first time, by not writing the code on the window before he dies. So it's not their fault they didn't survive, it's his fault. That gaping flaw in his assessment isn't raised by anyone.
The teacher also shows himself to be a psychopath - no remorse is shown for shooting the kids, not even an apology for not letting the others say goodbye. That's murderous, psychotic behaviour, which is reason enough to exclude him, logically, nevermind emotionally. That isn't raised either.
He asks them to choose survivors based on given data - but doesn't provide any data on himself ("I'm a wildcard") then punishes them for not choosing him, which is completely irrational.
In the second iteration, things are revealed about them that couldn't possibly be known anyway, eg. someone will get cancer in 3 years, or someone will live to 100 and won't ever get sick. It's stupid that things nobody can know should be taken into account.
Third iteration, the girl had "remembered" the exit code from the previous iteration. That's just completely silly.
And so on.
But I got the allegory in the end, and liked it. I just didn't like all the obvious flaws in logic, when it's supposed to be an advanced philosophy class for smart people, so the journey to get there was an intellectually frustrating one.
The scene where the teacher was dying, then dead, outside during the first iteration, was very affecting; almost painful to watch. I think it would have been a great movie if the audience had been reeled in more emotionally like that, to make the proceedings feel more real. For me the ending, also, where he considers his own three "thought experiments", was touching and effective. It just a shame the rest of the film was so jarring because of all the irrational premises.