Clay model
I'm going to try to be thorough. I think the antennae set the bar: they are well modeled and they look smooth and organic, as if a real creature would have this exact structure. The overall head shape as well is good.
The real problem is the extrusions and intrusions. It looks (to me) like you made the head, and then "sculpted" the ear features, the mouth, the eyes and the nose. This method is very messy, as you can see the ear-channel is not straight or smooth, but "noisy" if you will. The mouth has that problem, too, and the nose has a lot of discontinuities. Honestly, most of these problem can easily be solved by "smoothing" all the features that you sculpted.
I'll compare this to making a model with clay. The head and antennae look like you spent time and effort on their shape, but the other features look like you sort of mashed pieces of clay onto the head to make it look recognizable. If this is the style you were going for, I'm okay with that, but then you should make the antennae and the chin also look "noisy".
And that line down the middle? That's a "normals" problem: the faces are "pointing" in opposite directions, so the smoother doesn't really know what to do in the middle.