Where to begin? One of the things that makes Shakepeare's depiction of Richard III and his climb to the throne is something that those of us today call historical revision, or the rewriting of history.
Richard III was not a saint by any means, but nor was he the coniving, ugly, deformed, and diabolically evil man he was deemed to be in Shakespeare's play. Shakepeare has created a monarch we love to hate; he inpires hatred and infuses the reader (and I'm sure the audience when appropriate) to cheer against him.
Shakespeare used mulitiple references and shot numerous unsustantiated accusations at Richard III in this play. The executions of hastings and a number of others are fact; they happened, but Shakespeare doesn't explain the reasons or the acts..... you have to understand the period's history in order to do that. Shakespeare even goes so fat as to allege Richard had something to do with the deaths of his wife and son..... makes for interesting reading, but it's far from true.
I could go on and on, but I won't. Shakespeare should be commended like all true artists in the sheer perfection with which he entertains. Every deviation he afforded history proved to make the story more compelling. If I had to compare it to a modern work I's use Braveheart as an example. The film was spectacular, and it was compelling, but it deviated from the truth and exagerated for the sake of making a more interesting movie. I myself never see the need; no story is better than the original. I think my biggest problem with Braveheart was Wallace's quick affair with Isabella (future Queen of England), and her subsequent pregnancy which was introduced to Edward as he died. Completely untrue, Isabella was nine years old, had never met William Wallace, nor would she ever have been sent into a situation where she would have met him. Compelling? Yes? True? Absolutely not!