Even if I too think some elements were somewhat off (like everybody deciding to do crazy things without doubting even a little about their informations and Mad Aya being too much powerful), I liked the character interactions and the fight scenes. Pretty interesting scenario though!
Despite all the mess, I'm also happy that Aya - and Reisen, for that matter - didn't completely snapped into insanity, as it seems eveything ended as usual. That would be pretty sad and tragic (not that I'm new to those types of things in some Touhou doujins lol).