Sounds really cool!
(note: suggestions below)
The only thing you should be concerned about is the transitions. I'm talking about between the intro and when the powerchord guitars enter, and also when the vocals enter. It's just a bit jarring, so here's some suggestions for transitions:
1. Build up volume in the previous measure (or two perhaps) dramatically so the change is less unexpected. Also put in a drum fill.
2. Have a break. For example, the drums hit a snare and all the instruments pause for 2 beats.
As far as mixing the only suggestion I have is to add a tad of cathedral-sounding reverb to that high vocal.
I wanna see if I can mess around with it in my sound editor, okay?
