Just some thoughts.
The head movement does not really seem to relate to the words. Its sort of moves around but is not emphasising the dialogue at any point. I would try and lose some of the movement, and only hit a couple (or even just one) of key points. The most obvious one to my mind is the ‘smart’ word. Hit that one, and then perhaps the s in s-mart. You have a little sideways jiggle on the second ‘shop’ which is a also a little late and should be more of an up down action (if you leave it in…) Even that is a little predictable and might not work so well, but it gives you a starting point. The head movement is also very linear and computery. Try offsetting some of the channels so that they peak at different points. Eg. Shift the z-channel back a couple of frames. That should get rid of that roboticky sort of feel a little.
The sync is ok so far, but really only works for me when he says ‘shop s-mart’. The earlier stuff doesn’t quite hit the mark. The lips also seem to bounce a bit on the first ‘shop’? I’d go back and rethink the initial sync, as it doesn’t hit the ‘notes’ so to speak particularly well to my mind.
Also, the blink is sort of just stuck in there. Blinks are always done with a purpose (in animation anyway). I’d move it so that it coincided with a head movement, or maybe even just speed it up. Its a fairly slow blink. I’d crack it out a bit quicker.
This is all just my opinion btw way. Use it or not as you want.
In any case I hope it’s useful.
Cheers
Shaun