I liked the setting of being underwater in a sub exploring a lot, the story kept me interested in getting to the end. The twist was a fun reward for hanging on.
Gameplay-wise I think the ideas were great (exploration, upgrading your sub using pickups you find, getting new abilities) but the execution fell short for me. Mainly, going back to the ship for every upgrade felt tedious and unnecessary, especially after finding the claw. A smaller environment or more things to see/experience might make it more interesting. Also I think more things could have been conveyed clearly to the player, like when they take damage.
My favorite part of the gameplay was the fight with the sea monster (swordfish? I'm not sure lol), that was really fun.
The music and sound could have been more developed, what's there is short and doesn't add much to the experience.
The art was good, I really liked the way the light from the ship tapers off into the water and the vignette as the player goes deeper and deeper.