Excellent. Polished, juicy, beefy feel. Challenging without being unfair. The medals add a nice touch of added difficulty for the people who want to push themselves. Keeps things fresh and interesting at a fast pace with changes to weapons and level design. Particularly liked the later levels where considering your position in that 'bullet hell' kind of way was more important. An addition I would make is to add a targeting reticle for the mouse cursor. One criticism: the grenades never seemed to quite go where I expected, felt like the were clipping off corners unexpectedly. Really well done.