The movie felt very repetitive; Tippi has a small moment of triump, then Hitch finds a way to humiliate her, and she gathers her strength and carries on. Repeat for 91 minutes.
Slant found value in it:
"Early on in The Girl, which probes the relationship between Alfred Hitchcock (Toby Jones) and his leading lady, Tippi Hedren (Sienna Miller), the esteemed director gives his screenwriter a piece of advice: The audience doesn't want a character they can identify with; they want glamour. That HBO's new film manages to heed Hitchcock's recommendation without being nearly as enjoyable as any of his films could be seen as a failing, but in fact, it's a deliberate and somewhat remarkable accomplishment. This is Hedren's film, told through her eyes, and in spite of all the glamorous costumes and set pieces, it succeeds at being a thoroughly harrowing exposé of Hollywood patriarchy run amok."
http://www.slantmagazine.com/tv/review/the-girl/361 For me, From the Journals of Jean Seberg is a more engaging film covering some similar territory.
Jean Seberg returns the camera's hard stare
"The gods who nurse this universe think little of mortals' cares. They sit in crowds on exclusive clouds and laugh at our love affairs. I might have had a real romance if they'd given me a chance. I loved him, but he didn't love me. I wanted him, but he didn't want me. Then the gods had a spree and indulged in another whim. Now he loves me, but I don't love him." - Cole Porter