I saw the third preview last night. I'm probably not the best person to review John Douglas Thompson's performance in the title role, as I have never seen the play before and have no comparisons to others' performances, but he was very good. Thompson is totally comfortable on stage, and his range, from Hamlet's barbed quips to his uncontrolled anguish, was impressive and compelling.
The characters wore modern dress. (At one point, King Claudius is in exercise clothes.) The scenes with the ghost are well-directed and acted, and Steven Anthony Jones - as Claudius and the ghost - is a standout. Graham Beckel, as Gravedigger 1, steals the show for a bit. Teagle Bougere, who has been in a lot of Shakespeare in New York, is a good Laertes.
As I assume is common, the play is somewhat truncated and lasts 3 hours and 15 minutes with intermission. Even though I spent the week reading Hamlet, it's still striking to hear the language from the stage.