Even on the 4D we had at 20 weeks, there was only one "good" picture of her, the others made her look like scary baby.
that's normal. your little one is all squished and cramped in there w/o much room to move around. im sure its all fine!
At our last u/s, @ 34.5 weeks, our u/s tech showed us baby's face; she just looked right at the u/s probe. It looked frighteningly ugly. I am trying to console myself by the fact that it was 2D and that many u/s pix look kind of weird. You have to take into account that your baby is basically floating in liquid and all squished.