It's an interesting play and its made by its language and its individual scenes. It harkens back to classical Greek theatre with the women in the play often playing roles similar to the Greek chorus where they comment on the action.
Its interesting to think of the play as a kind of proto-Lear. Richard's physical deformity is emblematic of his psychological deformity. It examines evil that is almost unmotivated and demonic. Shakespeare often was concerned with moral themes. He often examines the motivations which lead people into evil, most famously in MacBeth. He was also interested in the other kind of evil, the evil of say Hitler, where the evil actions of a person are so monstrous and perverted and undermotivated that they seem like an intrusion of the satanic on the universe. Richard is continuously linked by others and himself to hell and the demonic. The play examines how this demonic force emerges out of a society torn apart by civil war and imploding in violence. A society that can only be cleansed by the expurging the demonic figure in its midst.
The play can be seen as tudor propoganda, but it is more than that. It is a play about pure evil, something which unfortunately exists. It has beautiful scenes and compelling dialogue, however it does not reach the heights that Shakespeare is capable of and it is middling in quality of his plays. That of course means that everyone should read it.