By what we saw until now, Shiraishi good points are: He's invisible to everyone, excepts for Kubo, which is a great source of amusement for her, he's honest, he's funny, easy to tease and talk to, when she's with him, she never gets bored, he make effort to make her comfortable around him (and a last one, i put it in between parentheses, because it's more of a theory: Kubo is the only one that saw Shiraishi face, i mean his real face, and not his mob face. Shiraishi usual face, the one he shows to the readers, seems to be more the way others see him, than what he actually looks like. Since he's invisible to everyone, there's no reason to why they would hold information about his facial characteristics, so i think their brains just fill in the blanks for them, and the face they see is not his real face, just what he looks like to the average person, who can't perceive him)
Also, Parsley is really good