Very disappointing given the cinematography and acting were very decent that the writing should be so poor. There is far too much mytholigising of the historical facts. Billy killed a lot of innocent people with no great motive other than self preservation. This gets glossed over while imaginary good motives are attributed onto him that he never claimed for himself. It's the Michael Corleone syndrome writ large. We can't accept that killers like Capone don't really have a rich inner life and could have been Captains of Industry if life had treated them differently.
There really wasn't so much sharpshooting in gunfights. Most victims were shot in ambush and in the back as gunmen prefer to have the odds in their favour when they strike.
Deadwood and The Wire can grasp this so much better and still give the perpetrators of crime some back story about the adverse circumstances that live under but they don't veer into the glorification of killers. This series did not even try.