I really like the game. It's a lot of fun, and there are some spots that are really challenging. That said, I couldn't finish this game. Not for lack of trying, mind you. I've explored every ounce of the map except for an area behind a locked door. I managed to get a key that should have unlocked that door; but it didn't. Even though I have the key, it won't let me through. Is there something I'm missing? I'd really like to be able to finish the game. That's the only reason I'm not giving the game a full five stars.
All that aside, what I did get to play was a lot of fun. I especially like the throwing knives. >=3

Firstly, I should offer something constructive. Like some people here are saying now and then the environment will go all grey and all you can see is your character. In that situation I've actually found collapsing it and then expanding it works wonders, especially since it saves progress when you do this.

That said I wanna praise the game and in a big way. I'm gonna go ahead and remind people of the Metroid series. A HUGE part of why that series is as big as it is today is because of the games general environment. It MAKES the player feel alone, desolate, and abandoned. It also does something that this game does, where it burrows certain places into your mind because you cannot reach them. So that when you ARE able to, that's the first place you go. Not only is this great for the immersion factor, it does wonders for the game itself. Don't loose that in the sequel.
As for the plot I loved it. The only thing that wasn't clear to me was the bombing of the city. I would have liked something to help clarify that a bit more. It's hinted at a lot, but not in the proper way to make it obvious enough. I'd also love to find out WHY it was our character that was brought there and not someone else.
One last bit of advice involves the map. It's not giant but it isn't small, not at the speed the character moves. A really helpful tool would be one that let us bring up the map and click on rooms we wanted to go through. But again, that might hurt the immersion, so maybe not? I don't know. Either way it was a great game. You only loose half a star because of how frustrated it made me when I didn't get more specifics on the story that was sooo good.