It's not very good.
The underwater sections are quite pretty.
Sometimes there is innovation in the underwater maps.
The maps are generally fairly big and are mostly single maps that sometimes wrap around themselves nicely.
There is some variety in the enemies but they're mostly reserved for special encounters, which is maybe good because many of them are irritating.
Headshots do high damage.
Headshots do high damage. Stepping out from cover to go down to one lucky shot, really gets old.
It's a generic over-the-shoulder shooter.
Supposedly it's a PC native but it sure feels like a half-hearted console port.
Controls are poorly chosen and can't be remapped, examples: mellee and grenade are next to each other, alt-fire and change weapon are on the same button (mouse scroll button). These lead to all sorts of accidents under pressure where you change to your pistol instead of using a powerful attack, or drop grenades at point blank when melleeing enemies.
Many enemies have stun-lock and you just get to watch for a few seconds before you die.
Some of the battles are very. very hard. I repeated one fight for about ten hours in total. I think most people would have given up. It's usually worth using glitches.
Hacking enemy drones is a thing but it can be very hard to pull off sometimes as it randomly fails without reason. Sometimes this happens many times in a row and you die.
The surface maps are things you've seen before many times.
The armour's glowing health meter is a fairly direct rip of Dead Space, maybe that doesn't matter though.
You move very slowly when leaving cover or changing direction, there is no run button and the 'roll' mechanic is pretty useless. This leads to you slowly taking small steps in combat when you try to retreat. Retreating is generally suicidal.
Mellee is a one-button kill, assuming you didn't fumble and hit grenade. This makes the mellee enemies (one human, one drone) more or less harmless. Enemy mellee attacks do light damage and you have maybe ten seconds to hit 'f' when they attack you before they might succeed in killing you.
The various unlocks that you get in the game (infinte ammo, golden gun) can't be used. They literally do not do anything when activated.
The game isn't exciting and doesn't really have anything new. Hydrophobia did water better, there are dozens of shooters that do combat better. Being second-best to Hydrophobia isn't harsh criticism though the surface game isn't exciting so really, I should have just played Hydrophobia again.
The biggest con of all is that getting the game working in the first place requires some non-trivial research. I'll save you the time, this game will not run unless you implement a firewall rule in Windows to prevent it dialing home to the original developer's website. They do not support the game anymore (sold it to some third party that put it on steam) so the steam version will not run in its released form. You must make a firewall rule to block the game's .exe from internet. This also cancels multiplayer but since no one is playing it in MP anwyay, that's no big deal.