Ooookay.
First of, the whole movement is weird. He switches from righty to lefty right at the last instant for no aparent reason. It sure looks like you did your research, though.
I know samurais are supposed to be stiff, but some anticipations to certain movements would help, specially the down slash, otherwise his weapon would seem weightless.
Nice work on the rebound of the sword right at the last 4 frames or so.
You nailed it at the timing, if he didn't look like a samurai, people would still recognize him as one.
Flash has a feature called onion skin (I think), it helps you see a transparent fersion of the previous frames, just like in traditional work, look it up, that would help you avoid shifting in position and deformations on the character.
All and all, it's still pretty impressive for someone who has been using flash for a month, just keep up the good work, I think you've got what it takes to be an animator.
Hope I didn't sound too much of a hardass. Cheers!