It is kind of a fun exercise. There were two characters (I have not seen the movie yet) that I disagree with: One is James Taggart, he is too young and slick looking, and the other is Ellis Wyatt. That guy they casted doesn’t look anything like the book’s description, but...I can live with that...:)
I can’t remember the description of Ellis Wyatt, but I found the actor believable as a Western oil-man. And his delivery of the last line in the movie was perfect.