As an early representation of the turmoil of the 1960's that followed, Diane Arbus (Nicole Kidman) can be excused as an early flower child. The film itself deserves no such latitude. The lack of character development, motivation and justification for the character's behavior makes the movie very disappointing. I sat watching and waiting for some explanation of the bizarre actions only to find that Shainberg was letting me peek into a story that must have been someones inside joke. That the few facts presented did not match Diane Arbus' life very much did not help to clarify things either.
The washed out Art Direction in Diane's 'normal' life was nicely contrasted with the brilliant colors in her 'awakening' life with Lionel. And the trap door stairway was a nice demonstration of Diane's attempt to inject her new life into her existing family (However, I don't see how that trap door in the ceiling of her dining room could directly connect to Lionel's apartment which was two flights of stairs up from her's).
Maybe my analysis is a little too literal in looking for some character development and relationship understanding that goes beyond one sentence or one comment. I also would have liked to see at least one of Diane's photos as well. I won't wait for the sequel.