This is a nice take from the usual portrayals of Sonic I see on deviantart. His unusually intense expression and his action pose give me the feeling that he's either indulging in the power that his dark state, Dark Sonic, grants him while trying not to completely succumb to his rage or that someone has brainwashed him, and he's struggling to break free. Either way, I personally think that you have done a great job of making me feel this way about the blue speed demon through a well designed background, his expression, excellent lighting, and great attention to details throughout the piece, especially on Sonic's body. Spectacular job!!
jk