oh man, what is there to comment on... or rather, where to start...
* no background
* forehead protector has some weird details --> bolts, konoha mark
* the skin and hair look flat and the color hues are... not my taste, to put it gently. same goes for bandana and iris
* the white and orange of his collar are flat, so is the eyewhite. inside of collar is skin color for some reason.
* jagged lines
* inside of mouth is pitch black
...so yeah, there's a bit to work on here...