This game is a lot of fun at first. It really gives you a great chance to flex your strategy muscles, figuring out the very best way to maneuver your squad and take out an enemy force. It's very rewarding learning what tactics do and don't work. However, there are a few issues that stop this being a great game.
Firstly, the difficulty. This game is bloody difficult. I've beaten Starcraft on normal difficulty, I've beaten Mass Effect on insanity. But not only is this an entirely different kind of game, it's just inherently punishing. Your squadmates die far too easily even with the best armor, and once they're gone they won't come back. If you lose even a single veteran squad member on a mission, you're basically screwed until you can train up another one. I resorted to just making a save every mission and reloading it whenever one of my people died.
Another problem is the repetition. There are only two or three types of areas, and you'll get sick of the same old reskins. The battle mechanics don't change at all through the course of the game, the same tactics apply to all new enemies. Take cover. Shoot. Grenade/rocket if they group up.
And finally, there's a really terrible lack of direction. It's not that it doesn't hold your hand, it's that it just throws you out there. You don't even know what your objectives are half the time, other than just engaging in random battles and assuming the plot is moving forward. Whatever plot there is, anyway. There really is no plot. They tried to make a couple of characters interesting such as your head scientist and engineer, but failed miserably. They have no depth whatsoever.
Overall, you should give this game a rent. You'll probably have fun with it for five hours or so before you get sick of doing the same old thing, and getting beat over the head every time.
I highly recommend this game if you're into turn based strategy games because every aspect of gameplay integrates into each other very well. You will be considering your decisions very carefully and gives the fighting a sense of tension, excitement, and euphoria when things go exactly as you planned.
I highly recommend playing this on another platform since the PS3 version crashed on me on average once per play session.
The PC version is probably better since mouse + keyboard works better in a game like this.