Could you use this spell to turn an undead back into a human (or whatever) - bypassing the whole willingness to be raised issue? Looking at the modifiers:

Same kingdom (animal, vegetable, mineral) +5
Same class (mammals, fungi, metals, etc.) +2
Same size +2
Related (twig is to tree, wolf fur is to wolf, etc.) +2
Same or lower Intelligence +2

The last three can be considered fulfilled, except maybe related and spectral undead. Class is hard to argue unless you consider humanoid to be a class. I'm no sure about kingdom though - undead aren't exactly animals but they are closer to them than minerals and vegetables.