I think that Houtarou finds Chitanda intriguing. Not
just because of her lovely looks, although that is a factor, but also because of her unusually charming and disarming mannerisms, consistently upbeat nature, and insatiable curiosity.
But while Houtarou finds Chitanda intriguing, I don't think that she's gained his
respect yet, whereas Satoshi has (at least to some degree). I think that Houtarou views Chitanda as someone who's naive, a bit sheltered, and a bit lacking in good reasoning skills.
Given that this
is a girl who was once seriously puzzled over why she became angry with a teacher... I can't entirely fault Houtarou for his views here.
Chitanda is a charming character, and I do think she's intelligent in a basic book-smarts way, but she does have a certain cluelessness to her at times.