more on facial expressions


All this is an offshoot of the perennial problem of describing a character's reactions. You can use the short hand: his expression gave away his surprise, or you can try to be more descriptive: his eyes bulged and his brows climbed half way up his forehead.
The second one is clumsy; the first one is empty. Also, without considering what the mouth is doing, you don't know what kind of surprise we're talking about: happy, unwelcome, embarrassing. This first mouth looks embarrassed to me, lopsided, teeth flashing. The second one looks like a happy surprise on the basis of the wide smile, but it's also uneasy.
I really do have to start making notes of how this is handled whenever I'm reading. It would be a useful database, and I think quite a revealing one.