Amazing
The difficulty of this game was quite interesting... I got through all of the stages 1-19 quite easily, only getting hurt once or twice the whole time. But then when I got to Mr. Big Bad Boss it took me 5 or 6 tries to beat him (Not that I couldn't figure out HOW, I guess I just suck at it :P) Anyway, on to the details.
Graphics: I love the graphics in this game. Your art style reminds me VERY MUCH of mine, so I can't get enough of it.
Style: I've NEVER seen any games on NG involving a Venus Flytrap, especially not a defense game. I also like the little backstory to it, even though I didn't go to the external website in the menu to read more. I only gave style an 8, though, due to lack of an ending.
Sound: The music wasn't REALLY anything too special, and neither were the sound effects.
Violence: There wasn't much violence either. I only gave it a 3 because of the guts. The ones that come out when you kill the boss in particular.
Interactivity: Yawn, moving on.
Humor: Wasn't very humorous, nor do I believe it was meant to be.
One last thing... Why are reviewers asking about the story when they can just go back and read it in the game..? The fact that they didn't bother reading the story when they played implies they don't want to know, but then they go and ask here..
Anyway, awesome game!