I cannot recommend this game enough. It definitely not perfect--I had numerous complaints about its audio mixing--but the gameplay is so good. It does the System Shock/Bioshock formula extremely well. If you're going in for your first time, push yourself to experiment. The game is very good at letting you do things you maybe normally wouldn't think of.

Gameplay spoilers!

For example: There are times where you are locked out of a room in need of a keycard or passcode that you need to come across. Sometimes this can be mitigated by a simple swing of your wrench can break the glass; many people will likely figure that out. Sometimes, that locked room has glass, but it has bars preventing you from entering after breaking the glass. This may lead those who use the typhon powers to transform into a small object and move between the bars to get inside. Now, what do you do if you don't have the keycard/passcode, or have psionic powers? Well, there's a "weapon" that you can use called the Huntress Boltcaster. It's a toy gun that shoots foam crossbow bolts. You can use this to shoot the button on the inside of the door to open it. Incredible.