Sven, you just need to get out of your attic more often. Nobody was commenting on his sprite, so I pointed out my biggest complaint and at the same time expressed the negative effect I thought it had, in one concise sentence. Is not the OBVIOUS thing to do about it to use different colors??? Next time I'll ignore his request for C&C like everyone else. PUNK SCHNITZEL!!!
Furthermore, the cape . . . it kinda reminds of how as younger kid I'd draw characters conveniently standing in a hole or behind a wall in order to avoid having to draw their entire body. The character here is fairly interesting so I automatically want to see his entire body and the masking cape feels unnecessary. If you don't want to rework this sprite that much, how about a little cloth upgrade - give that cape a more realistic flowy cloth appearance, some actual wrinkles, rather than those evenly spaced creases; almost looks rubber.
Colors. You sure you need 20? Not that big of a sprite. Notice you've invested the largest orangey ramp to the smallest parts of the sprite. Ought to be the other way around.
Random idea: insignia logo on cape.