Nice,nice!
Your improving is really marked, from the first drawings to the lastest there is a lot of difference!
For a first ever animation this is really good!
The only thing I think I could tell is that the music stopped near to the transformation during my viewing, now this could be 'cause you did not set "Stream" in the frame properties, you probably just let "Event"...And this is all my advanced criticism!^^
It is visible you put a lot of effort in this, therefore you get my 8/10 and 4/5.
Bring it on, you are good!