Mommie Dearest doesn't do 100% justice to the legend Joan Crawford was. However, I can't hide the fact that it's sensational and at places unintentionally funny (which is amusing itself).
Diana Scarwid (plays Christina Crawford) impresses while Faye Dunaway as Joan Crawford goes over the top many times. What this film largely reminds you of is Joan's legacy as a Hollywood superstar who "made it" in silents as well as talkies. She deserved a better film.
Having said that, if I had to rate it as a critic, I would still give it 6/10.