Movement control feels great, but the attack animations of some weapons could use some tweaks to improve overall accuracy. For example, I find it quite annoying that the shooting angles of sniper rifle are discrete "states" rather than a continuous 360-degree circle. Some modifications in mechanism might fix that.
Also, think about adding some item descriptions to avoid confusion, then use your imagination to make long game sessions more interesting (e.g. special enemy waves, permanent upgrades, weapon reloads...)