Meh
Good choice with the Metallica, but hell.... that riff gets annoying after a while. Try expanding it or choosing something that isn't so obvious when it repeats, I kept waiting for the lyrics to start.
Also, like many people said, turning around would help. It didn't seem like the tanks did much of anything, since I'm pretty sure the projectile it shot went straight through me with no ill effects more than once... it'd be cool if you could walk on them too. And as a last note, the guns seemed pretty worthless, since I couldn't shoot the bad guys to death without getting shot in return. By far the best strategy for survival was jumping over their shots and relying on grenades to clear the way