I like the music.
You culd probably replace the visual cues like reloading with a sound.
Or change the ammo count to reloading to keep it out of the way.
I think the zombies should moan, so when you get closer to a group you "hear more"
You could make the zombies "hear" so the louder the bigger the waepon the more they are attracted to the sound, would give a good reason to use smaller pistols or silenced weapons near large groups.
But all in all I think it's a great project.