nice job, man.

speed modeling is great practice. Turned out pretty awesome too. But I'm a bit confused about your target - why are you rendering the shaded at such a low tessellation?

It looks really nice from the front with the exception of the perspective distortion and a big contrast in edge density in some places (like the eyes) It loses a lot when you spin it to a 3/4 view though. front+side views are nice, but you also have to fill in the blanks and understand what the form looks like from angles. The biggest thing I see is that the cheekbone is coming too far forward, find more refs and check the relationships between the eyebrows-cheekbones-modiolus and so on.

Anyway, another thing I wanted to mention was the ear, it's really under defined and placed a bit too far back, it looks like. For a speed model, that's probably okay, but if you're going to start it you gotta finish it!

keep it up!