A more interesting idea...

...would have been to try and show the split between Kuklinksi's vision of himself -- devoted family man -- with the reality that his family was terrified of him.

Maybe that would've been too difficult to depict. They tried something like this in that recent Linda Lovelace biopic, and it didn't really come off, but that's what the real Kuklinski story seems to be: a sociopathic professional killer clinging to the great lie of his own humanity. Has he even convinced himself that this artificial persona is real? Or is he consciously lying about it even though he no longer has anything to lose?

Movies like this miss the mark when they assemble a great cast but fail to deliver an original, challenging take on the characters. I can watch Shannon do just about anything, but it seems very lazy to me to choose to tell only one side of a controversial true life story, when it's the controversy that makes it most interesting. Don't just to try to remake Goodfellas. Explore the paradoxes.