I've always been a fan of top down shooters, and yours is a great example of some of the things to do, and, unfortunately, some of the things you shouldn't.
First of all. The music and art where great, really matched the gameplay. The gameplay itself felt juicy, which is always good and I loved the fact that you could see the impact you are having with the blood stains on the ground. However. There are a couple of flaws. There wasn't an environment. All three stages felt like the same place, which makes the gameplay feel very repetitive.
Apart from that, you made a great top down shooter. I really enjoyed it! :)