Not the best, not bad.
Ok, this movie isn't bad but it could use a lot of improvements.
To start, better effects! You can search for Flash effects at Google or look at the Newground tutorials. Your effects really need to get better. :3
Second, make your animation smoother cuz now it really looks noobish. x)
3th, GRAPHICS! Please make them better. The characters look really bad and they also move stupid. The guns look really good btw, that's a really good job.
4th, the music was a little bit annoying but the sound effects are good. :3
5th, blood effects? The blood you made is just like some red lines, use some alpha or something to make it look more like real blood.
6th, improve the menu, don't make it just white with some text, do something with it! :D Add a BG or something but don't leave it just blank. :3
Overall, your flash skills could use a lot of improvement but it's a good start. Just keep practicing and I think you could be a good animator! ;D
Keep it up,
Bertn