Looks nice. Reminds me of Triax style mechs from Rifts. And the head is reminiscent of the trainer head from Robotech.
The only issue I see is that the ammo belt and it's feed into the arm cannon looks like it would be prone to failure.
The perspective is hard to see, I can't tell if it feeds out of the main body from the chest or if it goes around to the back (under the arm-pit). Either way, moving the arm around is going to cause some issues depending on how elastic the belt it. Further, hit's to the body run a large risk of hitting the belt feed.
You might try swapping the side in which the feed goes into the arm cannon and have it loop around to the back. This will make it look better and appear more functional.
I would say it's the feed belt that's getting to you. It struck me as looking a little less than right when I noticed it, but then, I can't draw them for shit myself.
"Doctors keep their scalpels and other instruments handy, for emergencies. Keep your philosophy ready too—ready to understand heaven and earth. In everything you do, even the smallest thing, remember the chain that links them. Nothing earthly succeeds by ignoring heaven, nothing heavenly by ignoring the earth." M.A.A.A
It looks okay as power armor, but if this is supposed to be a mech-- a manned vehicle instead of a cool-looking costume-- you need to put a LOT of weapons on it.
Those gun nuts do not understand the meaning of "overkill," and will simply use weapon after weapon of mass destruction (WMD) until the monster is dead, or until they run out of weapons.
They have more WMD than there are monsters for us to fight. (More insanity here.)