Shooting feels pretty decent, level design is quite tight and a bit claustrophobic at points, but I assume that's the intention. I like the pilot portraits in the corner, it's reminiscent of mecha games like Bulk Smash on the Sega Saturn, just need some animation and voice lines. A few of the UI stuff such as the compass could be scaled down I think, it takes up a bit too much of the screen along with the displays and the mech's cockpit frame. All in all a really solid foundation you have so far though, I'll be watching this with great interest!
Oh, and the DOOM inspired loading screen is also great, love that touch.