I'm assuming the transformation is static based on the Worgen model you choose. I want a specific human model, and it'd be nice to know what my Worgen will have to look like to get the desired result.
[edit for Blue post]
Worgens - Customizing the Human FormSupersquee!
You might not be able to customize your human separately from your worgen, but you will at least be able to see both at the same time so you won't be surprised when you zone in. We don't want anyone to have to keep creating and deleting worgen to get the look they want. (Source)