I'm sure somebody must have noted this, but I've made a cursory search and can't find it: this is an adaptation of Shakespeare's Julius Caesar, as the title surely suggests. Paul (Philip Seymour Hoffman) is Caesar, brought down by his subordinate Stephen (Ryan Gosling), who takes the part of the scheming Cassius. (His last name, Zara, is even derived from "Caesar" or "Tsar.) Gov. Morris (George Clooney is the idealistic Brutus, whom Cassius convinces to depose Caesar. In Shakespeare, it is Brutus who falls from nobility, just as it is Gov. Morris, here. Of course, everything isn't parallel: our Caesar lives, for instance, and will make $1,000,000 per year. That's probably about what losers get in our political world. We even have Brutus's adoring and serene wife, Calpurnia, in the Jennifer Ehle character. Though not all plot points or characters are parallel with Shakespeare's (nor need they be) most are.
I admire Clooney's decision, if it was indeed his, to have the "assassination" occur offstage, as it were, in the backseat of a car we only see from the outside, in a dirty alley, which is apt for the business being done there. Paul goes out with the garbage. I also like the last scene. Gosling's dead expression leaves no doubt about how Stephen's victory tastes to him. And there's one other thing. Stephen tells Molly that she has to go because she has made an unpardonable mistake. Then, he does the same thing and can't abide the same punishment he has so rigidly meted out to her. It's a fine irony, the one on which the story pivots. Makes you wonder which character found the best way out.
As modern political intrigue, the movie works exceptionally well. One can believe it actually happening today. Maybe Shakespeare's audiences felt the same way. Maybe nothing changes in politics.
The sexual indiscretion is, of course, an addition--not in Shakespeare. The criticism that this is a hackneyed plot element might be valid if it weren't handled so movingly, and that is all to the credit of Evan Rachel Wood, whose performance steals every scene she's in. Clooney, Gosling, Hoffman, and Giamatti are all excellent (what a cast!), but it's Wood who, for me, settles the question of how many stars this merits.