Good film but unrealistic
The iceman in the film is sympathetic, and has a family, makes it look like he's doing the killing to support the family. But the real Richard Kuklinski, if you watch the documentary, is actually a sociopath, pathological, cold-blooded killer, that has shown a tendency to kill even animals at an early age just because he enjoyed killing.
Imagine if the film is adapted more to the real Richard Kuklinski. I imagine this would be something Stanley Kubrick can tackle well. But this film falls into the same Hollywood antihero kind of cliche.