I thought it was Tarantino's love letter to Hollywood filmmaking of the past.
The main characters were well-drawn especially in demonstrating Daulton's insecurities fed by his alcoholism and his inability to recognize that he had acting skills.
The "alternative facts" created to change the "Helter Skelter" tragedy led to the director's use of savage violence that is his trademark. With the audience's knowledge of the Manson Gang's desire to slaughter innocent human beings, the methods employed by DeCaprio and Pitt were justified.