The title says it mostly, but to be more clear...
What would you say if a player asked to make a Fiendish Familiar (Fiendish Symbiont from the Fiend Folio) as his Sorcerer's Familiar?
Technically I know it doesn't fit the Animal or Magical Beast base for familiars, and I really don't think it would add anything as a familiar that it doesn't give the character anyway.
So I am thinking it really doesn't deserve status as an Improved Familiar.
I'd be interested in others thoughts and opinions please.