I know it is meant to be a tribute/fantasy, but with Kidman, Downey, etc in it I did expect a film worth watching. It is weird, strange, and decidedly offbeat. If you are expecting a film remotely about the real life of Arbus forget it, if you like fantasy, and Kidman in 50's style clothes and hair then it might be worth watching because she has to be one of the most beautiful/sexy actresses there is.
I know some people will like it being strange and i have to admit it is well acted by all concerned, very well filmed, just mot my kind of story line, but it may be yours.
Because it is well acted and well filmed I have given it 3/5, perhaps it is my fault for not being capable of appreciating the story line and ideas behind it.