The gameplay on its own would already be good enough. The stylish visual effects and music elevate it even further! I always like incremental upgrades in my games, and you've done just that and really well too! I tried out all four weapons and each one felt really well balanced... except for the nano swarm I have no idea what to do with that one. The range increase on that also seems like a bit of a noob trap.
There's so much variety in the enemy department too. With the big walls of squares providing a really nice "oh crap!" moment so you don't get too comfortable anywhere.
The fact that I stuck it through and played each weapon (some more than once) is a testament to how well you nailed the game-feel here! Well done!