The Platform was tight.
It's:
A Snowpiercer meets Cube meets Human Centipede type beat with some of its own flavours. Even knowing the synopsis, the setting is fascinating enough to act as its own character. The screenwriter's wink that hey, maybe we're saying something about society here, breaks through the fourth wall like paper and almost becomes a character in itself too lol.
Like a lot of Netflix originals, it builds suspense really well by creating an absolutely unwinnable situation with no light that's almost cathartic when the way they get the protagonist out of the hole comes. Another Netflix original trend the movie fulfills is having a fine but underwhelming third act.