Just watched this one (Italian with subs, Koch DVD). As a SW, pretty good - some great scenes, especially the crucifixion, & I love the song. As a loose adaptation of Hamlet, I was a little disappointed.
I knew it wasn't going to be a scene-for-scene retelling, but I thought some of the plot changes were missed opportunities. E.g. one of the most famous scenes in the play is when Polonius spies on Hamlet, hidden behind a curtain, & Hamlet stabs him, believing it to be Claudius. This could have worked really well in a SW (a shooting instead of a stabbing), but instead it was skipped altogether, & the Polonius character outlives Ophelia.
In the play Hamlet's friends gradually turn against him (Ophelia, Laertes, Rosencrantz, Guildenstern) but in Johnny Hamlet Ross & Guild are enemies from the outset & there doesn't seem to be a Laertes equivalent at all. His only friends are Horaz & Ophelia, who remain loyal throughout. & Of course it should have ended with some sort of rigged duel, like in the play. Surely there would have been an inventive way of putting that in a SW context.