Witness the Flip video camera. Accessibility can be key. Being "serious fun" often seems to be better than being a "serious tool."
I don't like it. You should trust a good text more than an avatar.
You see that they are just artificial creatures, because their speak sounds weird and their eyes have no expression.
I prefer to read a good text, so I can define the speed I read it.
Nice interface and you can try before registering. This would be great for making custom cartoon clips for children if only the voices matched the characters.