He is nuts in this, a total riot, and clearly loving his epic life. Some scenes approach a scale of madness, and it’s almost a parody of a Jack Nicholson role, but not quite. The masterpiece revolves around the whims of this lad, every other character in awe of him. Even if he goes full-Joker, he still manages to imbue Frank Costello with pathos, and dare I say it, tragedy. You can’t picture anyone else in the role, and it’s a tragedy in itself that Scorsese and Nicholson only tangoed for the one motion picture.
Best scene? Jack impersonating a rat. A decent impression.
Wanderings and ... wonderings. 