It's a pretty good start, but there are various things, I'll list them in the order they bugged me:
-brow/eye/cheek shouldn't be a continuous line
-i think it needs more shading or better definition on the nose, especially under the nose, but prolly on the bridge/around the eyes as well.
-ear should line up with the nose
-line up the mouth with the center of the face
-the collar is weird, right up against the face there, also, it doesn't seem to go all the way around his head.
-the hair on the left there is all random spikes, which you can do, but it has to follow basic rules for what hair can be like, or it won't really look like hair.

(this is mostly a guide to clarify what i'm saying, so don't worry if it looks kind of bad, the theory is sound)