There are two great stories here:
- A mafia guy is assigned to a union boss to both protest him and keep him in check. They become great friends, as do their families, but when the union boss goes against the mafia's wishes, it's our guy who has to kill him.
- A mafia hitman has combine his work with a family that abhors his work. Failing this, he ends up all alone in old age once his wife has died, as his kids have long abandoned him.
Both are great tragedies worthy of a Scorsese film, but I think neither story is presented optimally in The Irishman. Story #1 actually does best in The Irishman, as it takes over most of the film and really feels like its focal point once it gets going. Everything in this story is worked out properly - but as the story is neither the beginning nor the end of the film, it just kinda fades in and fades out, without a proper beginning and ending. Story #2 suffers worse, as there is no time to work it out properly (despite the film's enormous runtime). Most of it is told through voice-over throughout the film, and the hitman's family gets very little airtime. His wife and kids basically only get to offer brief responses to situations, barely get to speak, are often present mostly through their absence, and hence don't get to develop and remain one-dimensional. As a result, there is not much of a dramatic; it's more matter-of-fact.
So to me, a choice should have been made between three options: tell story #1 without the angle of story #2; tell story #2 as a family drama, without highlighting any particular hit (so no story #1); or turn the film into a miniseries with sufficient time to really tell each story in full, with fully developed support characters. But instead, The Irishman tells story #2 in the context of story #1 - and to me, the film remains a little flat and unfulfilling as a consequence.