Ehh..
Well, Ill give you credit for the graphics. They were nice. But, gameplay is just as important as making it look good. The gunshots got a bit repetitive, and so did the gameplay. Make sure the player is really understanding the story. Throw in some puzzles, to add some extra flare to it. Make the environments a little gloomier, and a little more variety in the sprites and SFX.
So, theres some tips in how to improve. Number one rule is gameplay is just as important, if not more than graphics.