I noticed when I was runnin' around in the shag that besides the enormous strength and speed of the 'beast' form, there is also a SHOUT for the werewolf.
Pressing 'z' utters a terrifying growl and does some kind of BLOOD SHOUT... I have Lydia as a follower and when I press Z it says Lydia is too strong and resists my Blood Shout (or something to that effect).

Anyone know what that is? Some kind of fear casting?

Also, does anyone know how to do the power move (where he jumps on the victim and slashes away at their face) or is it a random animation?

Shout is a fear effect....kind of fun in a dungeon where they run a way and you chase them down and eat them. Rawr.

And the animation is just that...an animation like the random kills with other weapons as far as I know.

The shout power can be truly awesome in some places. I once attacked a Spriggan clearing with that shout. Two Spriggan Matrons, three bears and a sabre cat all lay at my feet by the time it was over.

I've also read about other shouts you can get for your werewolf but I haven't gotten the necessary quests yet. They have something to do with the misc. quests you get from the Companions.

... s-w-e-e-e-e-e-t!

Maybe I'll use beast form more often now, this sounds sweet.