Good concept, very good production value, terrible implementation.
This movie had such good potential, but falls flat. A lot like White Chamber, which I watched recently as well. Could have been great, but it's not quite all there.
Let's start with the assumption that people who are starving will preemptively murder and eat each other. People are much more likely to starve to death than eat another human, especially raw. But to slaughter and eat another human? I can't see it.
The lesson we're supposed to learn is that the greedy top are bad and evil and that if we all just took only what we needed, then everyone would have enough. There are 333 floors. With two inmates per floor, that's 666 people. There's no way that the platform had enough food for 666 people with the portions that she was bitching about. Not even close.
Another thing that stood out is the idea that the higher floors would soil the food for no good reason. Mashing it, spitting in it, knocking it around. That's so stupid. They'd just grab what they want to eat and... eat it. What good does it do them to step on it and shit? It makes no sense.
If the platform goes back to the top every night, then why aren't more people riding it to the bottom to try to get back to the top? We have a guy with a rope trying to convince the next level up to help him climb out, but he won't ride the platform? C'mon.
tl;dr
People will starve rather than slaughter and eat raw human.
There was not enough food to feed everyone, even if they ate only their "portion."
People are not likely to defile the remaining food for no good reason.
More people would be riding the platform to get back to the top.