Ken Rudolph’s review published on Letterboxd :
This is the second HBO documentary I've watched this week about a son's attempt to understand and communicate his famous mother's story (the first was Jacob Ephron's paean to Nora.) However, in this case another film maker shaped the narrative; and all in all Liz Garbus does a good job of straightforward, chronological film making. Anderson Cooper, who spends more time interviewing his mother than being the subject of the film himself, is famous in his own right. But "Poor little rich girl" Gloria Vanderbilt is still alive in her nineties, still producing paintings that illustrate her fascinating, often tragic life. While not particularly probing, the film nevertheless succeeds as filmed biography. And as it reaches an emotional catharsis when it explores the mysterious suicide of Anderson's older brother Carter, the film touches a raw nerve of pain. Even the rich and famous are real people.