Neat game. Movement felt nice. Having a crosshair is really important - you mentioned you wanted an old school FPS style feel, but those old school FPSes either didn't have vertical movement with their look direction, or they learned very quickly that lacking a crosshair led to a really poor player experience.
I actively avoided health pickups when I could because hearing someone chewing what sounds like an apple right in my ear makes me want to murder everyone in my general vicinity. Some iframes after being hit would have been nice. If an enemy got in range to hit me once, they'd usually hit me three times in a row.