What do you like about paper prototyping? What don't you like? Why?

Well... This is definitely a lot more different than anything else I have ever done. It was not hard at all at least I didn't think so. I like the whole drawing part. I'm not great at drawing but I enjoy it. I don't even know if this is the game I will do but it was a start in learning how to do everything. =) But, that's all I have to say for now.
L8er.