The games best core strenght is how easy it is to pick up and to get playing right away. It immediately creates flow and feels good.
The game also does a good job explaining the controls, what just happened when I picked a certain thing up, and so on. It guides the player perfectly.
You could have been more effective with the stun ability. I tried it sometimes and absolutely hated using it because it stuns me myself for a short moment when launching it - making me actually weaker rather than stronger in fights where I really wanted to use it (when many enemies are around). I think it should really activate instantly and without drawbacks.
You should also focus more on getting the AI to work flawlessly. When many enemies are around, it happens quite often that a bunch of enemies decide to never attack again. They just give up (may be wise, on the other hand :-)
Overall, an incredible top down shooter!