I have read it multiple times. Michael Lewis has a way of choosing characters around which to weave his narratives. And get this right off the bat; it is all about the narrative. Humans are a story telling animal, and Michael Lewis understands that in spades.
The main character of the book is Steve Eisman, in the film played by Steve Carell (strangely cast as Mark Baum). Christian Bale plays Dr. Michael Burry (strangely cast as Michael Burry). Other main characters have new names, but some don't. Eisman's partners Vinny Daniels and Danny Moses retain their real names.
I have not yet seen the film, but knowing the book so well I wonder why the production company would want to make the story so confusing. Why not just use everybody's real names?
BTW, it is a great read. Lewis has a great sense of humor. And Steve Eisman offers plenty of opportunity to exploit that. His interaction with the head of a Japanese real estate firm is illustrative. Eisman, through an interpreter, is discussing whether he will invest in the company.
Here is how Michael Lewis relates it:
Eisman noted that the guy's financial statements didn't actually disclose any of the really important details about the guy's company; but, rather than simply say that, he lifted the statement in the air, as if disposing of a turd. "This is toilet paper," he said. "Translate that."
"The Japanese guy takes off his glasses," recalled a witness to the strange encounter. "His lips were quavering. World War Three is about to break out. 'Toy-lay paper? Toy-lay paper?'"
Yup! Eisman is brutally honest.
However Eisman is also the ethical center of the story. When the whole financial world is crumbling, and Eisman and his partners are sitting on the steps of St. Patricks, all having got extremely wealthy betting against Wall Street, it is Steve Eisman who takes no joy in it.
I recommend the book and I have some friends with whom I will see the film. One of them is a professor emeritus in economics. Yes, there will be plenty discussion and beer served after the movie. We all have read the book.