My favorite part of this demo was the stunned look of the birds when you punch them. I imagine them thinking: "I was just flying around minding my own business when this lady just punched me in the face!"
The controls were pretty easy to figure out and the music was very good. I also liked how the game was able to go full-screen.
Like crocdev said, I think the font could be better. It was very hard to read which made me want to skip a lot of the text. I think part of the problem is that the text screen is semi-transparent, so anything in the background is conflicting with the text in the foreground. So I would suggest making your text screens have a solid background and then pick a more readable font.
I liked how I had the option to attack with the mouse or the keyboard, but I found the decision to use "N" as the attack key to be a bit unconventional. I think space bar would have been a better choice. As a result, I often used the left mouse button to attack.