A bit of a challenge added to a typical FPS... not bad at all...
First, i hate it when games throw you right in to it and you get blown to bits or whatever because from that point on you automatically have some negativity towards the rest of the game. Yeah it makes for good storytelling but keep it brief and then start the game from the beginning and open with some frigging training for Christ's sake! If you thought about it, wouldn't that amazing, brief, firefight the suit just sucked you away from leave the player salivating for more?
Aaron Thomas said it best before me: "Another standard FPS with a gimmick". However, that 'gimmick' requires you to think in a fourth-dimension that no one has ever really thought in when they play an FPS. Time! And I am sorry to say that if you think playing any of the newer Prince of Persia games will prepare you for this type of experience, you are sadly mistaken. See, in PoP it just freezes or rewinds or speeds up all the while your character is somewhat unaffected by the phenomena. In Time Shift you character is able to freely operate within the phenomena. It ONLY effects your environment! And not just your immediate environment but the entire game is reversed, or slowed down or frozen. Buildings rebuild themselves, bullets and projectiles are returned to the barrel from which they came, allies are revived and now because the enemy is dead they will not die when you resume normal time.
You would think that with such a 'godly' ability, strategy is thrown out the window, that all you would have to do is freeze, kill, and continue on your merry way. However this game requires more fore-thought and split second decisions than one would care to imagine. Also, the developers were smart to make the duration of 'pause' to be shorter than 'rewind' and 'rewind' shorter than 'slow'.
Aside from your perspective. You also have to think about the enemies strategy. This is some of the best AI I have ever encountered. Of course, there will be moments where you can freeze time, sneak up, take the weapon and blast them away with out anyone being the wiser. Now try pulling that on a well-sized group, hidden from view, with a single turret under their command or several snipers up above you? When that gauge runs out you will most definitely find yourself standing out in the middle of the field, flanked, with a barrage of bullets coming at you. Sorry noobs, back pedaling will not help much in this game. The whole point of that is to put distance between you and the enemy. Kind of hard to do when they are not only advancing on you, but taking periodic bouts of cover and moving so they nail you from all angles or from behind or at least the sides. These guys are smart! Taking cover and waiting for that 'opportune moment' almost never works, because they will not give it to you.
So in summation, pick this game up! Play it the first time on easy to avoid frustration and to put you in the mindset of thinking of changing the flow of Time as a weapon. Your gonna need it!