Eh... have you seen any other multi-ending game-made-into-anime? You can go watch Shuffle and see some BAD scriptwriting. After watching Shuffle, Kanon is paradise for me.
As for the animation, it's far from what I call bad. It can't compare to many anime, but it's good enough to get you going with the story.
Damn, I didn't like Akira's animation one bit, but I saw the whole thing and well... ok I didn't like Akira as a whole either, but I don't usually place much weight to the animation when judging the anime as a whole. And the animation usually doesn't prevent me from watching something.
Oh yeah, speaking of Shuffle, I direct you to ep 24, second-half. If you think Kanon is bad, wait till you see THAT
