Sonic Fan Art - Looking for critique

So disturbing yet so cool!

When I read the headline I thought "Huh, this'll be interesting" And I was right! This is really cool, but also way out of my league, so I can't give any noteworthy critique I love his stance and how "gritty" you've made him. Never thought I'd think Sonic could be badass.

Edit: The only thing that bothers me is that his foot is very large, and the lines in the composition draw my eyes away from the rest of his body. The flares/sparks emphasize this. This might be what you're going for, but seeing how much detail you've put into his body, I imagine that is where you want me to look. The color and shape of his shoe kind of force my eyes to the bottom of the picture, and I kind of have to fight the composition to stay on his body.

I presume you put the foot on the right side for a more of a front perspective? In that case the leg itself is way too long, cause there should be a case of foreshortening
Other than that, I dont think I have any thing feedback that the others havent given yet

This looks really cool

Nice~ definitely not what I expected from Sonic fanart tbh xD Really cool stuff :3

Main issue lies in values really. Everything is too dark; there's practically no distinction between character, background and the ground he stands on and because of that it's kind of hard to sell where the main light sources are coming from making those highlights kind of useless and shadows barely noticeable.
Their consistency is confusing too. It looks like the most of the lights are coming from the left side and behind becuz rim-light, but bit of the shadow I can make out under him one would think light source is in the front/above, so pay attention to that next time
more notes below op:

• Colors: even though this is mostly monochromatic and gritty color palette adding more saturated colors could give character more powerful presence. I made colors more saturated on him overall and the rock/cliff? seemed too small for dynamic pose like that so I extended it.

• As far as perspective is concerned it would be more logical or... more balanced to have that leg to be more in the front and as such composition would have to be changed little too but I didn't have time to tweak that , but I hope even this much is helpful.

In conclusion, add more mid-tones, pay attention to light/shadow relationship and don't be afraid to add more "brighter"details to dark images. Good luck!