Eh
Well, a lot of it was based off the real Azumanga opening. You had a few good ideas, such as the bit where three images would appear and each turned a different color. I think it would have worked better if you used all unique scenes, because when you try to imitate the original, it inevitably doesn't look as good.
However: For a first flash, very nice. You finished it and it looks pretty good, so bravo! Work on more polished drawings and more original content, and you'll go far!