Al goes and does an in depth analysis of Richard 3rd (III), for example the opening sequence (about 15 minutes), is about the first line in the play, and by god I've never been so interested.
The whole film is an in depth view not only of the play but the way this (amazing) actor approaches the subject matter, to get inside the characters head by not just looking at the historical context of the play, but how a human being would react.
And as Pacino says this play has murder, incest, war, love, betrayal, witches everything, so it has allot to offer the actors and viewers.
I must admit, if you buy this film, it may take you ages to get around to watching it (it's not specifically action love or comedy so you'll never know when to watch it). But one day you'll sit down put this on, and remember it for the rest of your life.
What other sign is there for a great film.