Having now played and finished this game, this is easily the most impressive game I have played so far on the 3DS, for many reasons.
Firstly, the graphics are very special and would not look out of place on any console.
Secondly, the game itself works and plays beautifully. I have a few small problems with the aiming of weapons etc but that is down to the fact I struggle with any FPS games without a mouse and keyboard.
Lastly, the story and how it builds is fantastic. I was hooked from the outset and could not stop playing.
All in all it really does not have that "watered-down" feeling you sometimes get from games on handhelds. This game could easily be ported to PC, 360 etc and would still be a rich and rewarding experience on those platforms.