Really like the visual style of this, very cyberpunky, loved the neon. Balance wise, more of a cooldown on the bullet time is probably a good idea, with the multi-shot at the end - a cool feature, which reminded me of a talk I heard about a reload mechanic.
The gameplay is pretty straightforward, although I did notice that the geometry bounced shots in interesting ways, you could probably take advantage of that. Constantly backing up and firing works for most things, although it's a lot easier to dodge shots when you're diagonal from an enemy rather than directly across from them, which adds a nice touch of strategy to the backup and hold shoot pattern.
It was cool that there were a lot of different enemy types, but other than the shooters, it didn't matter much to the gameplay because the solution was pretty consistant no matter who you were encountering - keep your distance and fire at the closest enemy. The shooters were the most difficult. It seemed like sometimes your bullets would deflect theres, but it didn't seem consistant, which is for the best, as they were the most challenging enemies. It seemed like if you were in a bad situation dodging a shot could be impossible, which isn't terrible, since you have some control over your positioning.
The music worked fine. Don't do much 3d gaming/creating, so I can't say much meaningful about it other than the laser deflections being pretty random at times (normals?) The game played out well for me in the sense that I only got to the boss when I had pretty much mastered the game, was getting a bit bored with it and was more or less on full health. So I beat the boss and was done. Exactly the right pacing for me.