Very good
I really liked this film.
The world created was both really interesting and very depressing, for obvious reasons.
Eddie Marsan did a fine job. Raffiella Chapman was great, Rose McEwan also did well.
SPOILERS
The world created was odd, creepy and fascinating, especially the plant life.
The plant life that killed the two soldiers was very unique and pretty vicious.
It was also "nice" seeing the Citadel at the end, even from afar, as they are constantly mentioned.
I really enjoyed this world, despite what it has become. How we survive a potential future like this, is anybody's guess.
The film makers are not known names, but they did a great job.