I just had an ultrasound last week at 32 weeks ( i know it's a few weeks different) but you could see his hair and his face was so clear!!! I could see him moving his mouth and his big fat cheeks!
They don't always come out clear. With my first pregnancy, my daughter wouldn't let us see her. She kept her hand on her face. We had another a week later and she was the same. So no luck.
Hope you have better luck than us!
After 27 weeks they recommend having them as your baby will have fat so they won't look so strange. I had one at 16 weeks so I could find out the gender early. But as she had no fat yet it wasn't to clear. I could still make out features (when she moved her hand from her face(, But as your past 27 weeks you should see every little feature baby has so far.
I cried when I saw my baby in the 3d ultrasound. I felt like I was meeting her then. We had a few that were blurry but that was because she wouldn't sit still at points. But when she came out she definitely looked very, similar to the 3d ultrasound, minus she more detail in real life.