Lots of Potential, lots to improve upon
You have a great art style going here. The animation itself, as you may have heard, could be smoother, and if you feel like spending time making more frames for each animation, the movie will end up better. However, the use of black lines, and the color choice was very appealing. The blur and grain effects were also very nice. (how are you doing the blur? is it CS3 or CS4 flash, or are you using another program? It's awesome either way.)
The main thing I'd suggest would be to abandon the subtitles. I'd recommend recruiting some voice actors for something like this. True, you have music going and voices could undermine it, but I think its better to lower the music when the characters talk; the story is better that way. Voices would also require lip sync, but if you think it's too hard or are just feeling lazy, you can always just animate the mouth opening and closing. It can work well, and doesn't take that much effort.
At the very least, try using your animation to make story points instead of writing it in subtitles. For example, instead of writing "there's too many" you could show the character looking around, and all the enemies as a blur around him.
This is already a good piece of work, but I think you can improve. Good luck, I'm looking forward to your next project. Vote: 4/5 Review: 7/10