Hey Laozen! Just listened to your mix. I hope i can help you with my advice i´m gonna give you in a sec, cuz i had almost the same "issue" you have right now a while ago.
There is abolsutely nothing wring with your stereo paning, i.e. it doesnt sound mono! So that issue is solved. But, i would start out by getting a more solid, "glued-together" drum sound, since i have the feeling you kick drum and bassguitar are batteling each other. Try a HPF 12db/oct by 62hz, that should give the kick more room to breathe, since bass only goes down to 62 hz. btw, your kick is dominating alot, so turn that down a bit. So, to your guitars.... What amp did you use, and what cabinet? and how many mics? I hear that your guitars have a lack of body that is missing, the low-end rumble as many would say. Try a HPF at around 60-70Hz, bosst a bit at 85hz, a little boost at 1-1.5 kHz, and maybe also a LPF to get rid of some high end "fizz", if needed, ofcourse... This is not a guideline for you, just some personal tips of mine and how i work my guitars in the mix. If you recorded with 2 Mics, or double-tracked guitars, you could pan the guitars differently for a more "wall of guitar" sound, i.e.: Pan-Left: <100 & <80/75 Pan-right: 80/75> & 100> That should give you a nice wall of guitars. You can also try EQ´ing the individual guitar tracks differently. In the end, its all just about fooling around and trying alot of stuff out. Remember,...There are no rules in the world of audio ;-)
Hope that i could help you out!
Greetz