Tweak  one or multiple bones physics parameters on the fly (Pro)
collision on the entire bone
Bones react to movement and collision.
Super easy to setup.
Ability to stretch bones.
Ability to make a bone chain. (Pro)
Easy to tweak (it uses soft body under the hood).
Upcoming updates for free.
Enhanced baking system (Pro)
Dynamic Parenting (Pro)
Displacement (Pro)