It's a meta-film (The Irishman). I see it as a film that exists because of all other Scorsese/De Niro/Pesci gangster films, with Pacino added, because he's also a gangster-film legend. It's probably the last film with all these legends in one place and as such has a bigger, broader meaning. That's also why they put so much money into retouching these old farts and why audience turns a blind eye on these grotesque retouches. Because yes, let's be honest, they look kind of smooth, but sound and move like seniors for the whole duration of the movie. But you couldn't put a De Niro's younger face on a young actor's body and call it a De Niro performance.
So, as a meta-film, it's actually quite good. It didn't have the energy of Goodfellas, because it's an old farts' movie, but I was entertained. But I can't imagine how it would look to someone who doesn't have a clue about these old legends and films. It would probably suck.