Visuals: Good graphical fidelity, anatomy, and interesting concept. Well executed in my opinion.
Gameplay: Underdeveloped submersible undertow system. Felt frustrating when player couldn't predict random sub movements. Dissonance between player being able to delay sub in a skillful manner and absence of influence over the arrival time of the sub through random chance of undertow. Poorly executed.
Technical: Subs would sometimes veer off screen and be unseen because of random undertow direction. Not a huge deal but somewhat distressing.