A good way to describe this game, would be a Post-Apocalyptic-Underwater-Minisub-Shooter-Noire. The length of this description is appropriate given the ceaseless exposition and shoe-horning of story and game world terms into the script.
The game is not without charm though.
I would suggest it is a good reference for the would be game writer. The problem presented is that the player's interaction with the world is almost entirely made up of flying a combat mini-submarine and shooting at things. The experience itself tells little story without all the radio chatter and docking bay dialog around it.
As a result, many of the characters between missions will have highly convoluted political opinions or possess absurdly esoteric knowledge. Your point of view in the story is the role of Flint, who himself seems to have some very developed opinions. This makes it quite challenging to relate to the character effectively.
An attempt to make the game relatable seems to have been made in the form of a stylistic choice in the script. The game is strewn with metaphors and similes and delivered in a film-noire-esque monotone meter. Ultimately, the game asks too much of that stylistic choice to fix its over-riding problems.
It's a shame, since if you dig into the script, you can tell a lot of effort has been made to flesh the game world out, but it's just too esoteric. Players can handle detail, but they have to have been along for the ride that tangentially cobbles together that detail.
As for the game mechanics themselves - well your first problem on a modern system will be attempting to get the controls to work. If your optical mouse has a high polling rate which you cannot lower, you're going to have a bad time and I would suggest trying to use a pad.
There are some attempts at underwater physics in the form of currents and water resistance seems to effect the motion of the turret control (although, this could just be the modern peripheral issues). There is a ballistics system which is nice as you have to lead your target and you would expect water to have some effect on projectile velocity. The lack of speed boosting (at least up to the point I have played) is disappointing - speed as a limited resource makes for an exciting mechanic in this type of game.
On all fronts, Aquanox is a reference game that has a lot to teach the would be game-maker about the mis-use of talent. It is rough around the edges and perhaps ruined somewhat by modern computer equipment. But if you pick it up for cheap or in a bundle, I think it's worth a look.
My highlight of the game, has to be the drum & bass music with a 1950s bbc radio announcer accent layered over the top.