I like it! The gameplay is certainly skill-based enough that I found my score improving with each play as well as developing strategies based on the number of and type of enemies around. The music also adds a lot without being distracting or overpowering.

The only suggestion I would have would be to introduce some kind of "dash" mechanic to allow you to dodge rebounded bullets or large groups of enemies but to balance it by perhaps giving it a recharge time and/or having it "overheat" your weapons for a brief time so if you need to dash then you can evade death but it will stop you from retaliating for a while.  Maybe even a point penalty?