Hippolyta doesn't say a lot in the play - but from what she says first, it seems she finds the play itself rather ridiculous:
HIPPOLYTA: This is the silliest stuff that ever I heard
Theseus' response asks her to use her imagination to imagine them simply "shadows" (an Elizabethan term for "actors" as well as meaning something insubstantial") - and so inoffensive:
THESEUS: The best in this kind are but shadows; and the worst are no worse, if imagination amend them.
HIPPOLYTA: It must be your imagination then, and not theirs
Hippolyta's response is rather damning about the mechanicals' acting abilities - their imaginations are not working very well, she suggests.
Hippolyta also briefly comments on the moon - firstly that he is boring, and then that she thinks he shines with "a good grace". Yet it is Hippolyta who eventually feels sorry for Pyramus and buys into the "imagining" of the play itself:
HIPPOLYTA: Beshrew my heart, but I pity the man
So she starts off sceptical - but is eventually captivated.