Honestly it is an amazing game. It does have some issues (like tiny fov) but the atmosphere is excellent, it feels like a living, breathing world that goes beyond the game's parameters. While a very linear game, it turns it into a positive with a very claustrophobic feeling in the tunnels. You also learn the game as you go, which gives a true feeling of embarking on a first adventure that I've never had in another game. They tell you the basic controls but the nuances you have to learn for yourself.
It's well worth $5. I say buy it immediately.