There's an inherent problem with biopics in the modern media age: most of the subjects are people we know (or feel we know) intimately. Your guess is as good as mine as to how George Washington talked or walked, but everybody has a very specific mental image of Alfred Hitchcock. We know how he moves and how he speaks. For an actor portraying someone like that the decision must be made about how much of the performance is a Rich Little-style imitation.
Judging by this picture of SIR Anthony Hopkins as Hitch (from Hitchcock, formerly known as Hitchcock and the Making of Psycho), the actor will be straight-up Rich Littling this shit. Which could be okay, I guess, but does offer the possibility of being endlessly distracting.
Recently Michelle Williams did a fantastic job as Marilyn Monroe in My Week With Marilyn; the performance included physical aspects of Marilyn we all know so well, but Williams went deeper and made her a real person, not a free-roaming animatronic puppet. I think I would have preferred to see something like that in this Hitchcock movie (he says, having seen not a second of footage).