This interview with lead actor Gary Oldman, who plays George Smiley, is very interesting. I will say, the Brits do take there acting very seriously. In addition, consult this Atlantic article about the incarnations of Le Carre characters. Anyone who knows me, or who has had to sit through some spare time with me, will know of my passion for the two BBC productions starring Alec Guinness as Smiley (along with a superb supporting cast). However, I do like Oldman's take on doing a role that Guinness so made his own: classical roles, such as Hamlet, require actors to step into a prior great's shoes all the time. Who's your favorite Hamlet? Gielgud, Olivier, Burton, Jacobi, Branagh? Just to name a few. And while LeCarre isn't Shakespeare, these characters are rich. So, yes, I'll go, although Iowa Guru threatens a boycott. It can be tough, my beloved James Mason played Smiley in Sidney Lumet's A Deadly Affair (an alteration of the first Smiley book, A Call for the Dead, but it really didn't work all that well. No, it's a tough role to fill.
Here's the link to the movie site. Save me a seat.