When is a Coen Bros. film not a Coen Bros. film? I can imagine The Dude poring over this koan for hours, but the answer's quite simple: when it's "Gambit," the neo-screwball comedy directed by Michael Hoffman, working off a script by Joel and Ethan Coen.
The Coens have always been avid proponents of de- and reconstructing genre — be it the gangster film in "Miller's Crossing," the hardboiled detective flick in "The Big Lebowski" or classic westerns with "True Grit" — and "Gambit" seems to be a similar exercise in 1950s-60s British caper comedy, so much so that you can easily imagine Peter Sellers slipping effortlessly into Colin Firth's role here.
In fact, the Coens have covered this territory before with their 2004 remake of the Alec Guiness-starring 1955 classic "The Ladykillers," and "Gambit" itself is something of a remake, loosely based on the 1966 heist comedy starring Michael Caine and Shirley MacLaine. Given that "The Ladykillers" might have been the worst Coen Bros. movie ever, the only way to go here is up.