Quite nice so far. It has a potential. So what I noticed and disliked:
Visuals lacks lightning model (objects don't look immersed - main character is too bright, environment shall cast shadows / make units darker/lighter, many objects do not have shadows at all, maybe add some sort of antialiasing; there are no lightning effects to the sourroundig during explosions). Collisions can make you stuck (even on the first room). I may shoot most of the enemies before they see me, this make game a little static. I would add more enemies, maybe less powerful but make game more dynamic. Add more SFXs to the game. Some in game actions ends abruptly, there is no inertia in game - eg. enemy explodes, camera shakes, and then it stops at the end of the animation, add some inertia into it, soft the movement. Also explosions seems to not affect the player movement. The player is sliding on the ground during walk and there are noticeable slowdowns (however I play on wine on MacOSX, so it may be side effect of this). In the trailer there is a different version shown (hard shadows)?! And there are no sfxs in the trailer. I would add some background story to the trailer at least, make some plot to identify with.