I have yet to see a film with Nolte in it that I did not like. However, this being said, he's made a lot of films and I've seen just a few. In my minds eye I am keeping the images of his performance here and the one in "The Thin Red Line". Nolte has a a full range of acting talents. When it's necessary to shout he roars like a wounded lion. His best moments are the ones I treasure in actors: when he just emotes through facial, hand and body gestures, without saying anything. Having come to the conclusion that our present generation of actors, by and large, have no appreciation of what an actor can do without speaking, having no conscious appreciation of the mastery of Keaton and Chaplin, this generation of actors relies far too much on the mechanical wizardry of computers. Of course it is also just a sign of the times we live in. Had Chaplin lived in our times....who knows, he just might as well have become an aficionado of CGI tools.
I have not read the Vonnegut novel from which this film comes to the screen. However, the plot is not so far fetched or convoluted that we cannot follow the path laid, even with all its surprises. Of course on the outset it appears preposterous. However, it is also not impossible.
Consider these for starters: A Spy at the Heart of the Third Reich: He Extraordinary Life of Fritz Kolbe, America's Most Important Spy in World War II by Delattre and Prichard (look at Amazon for more details). Consider: History Undercover: Piercing the Reich: American Spies Inside Nazi Germany DVD (I saw this here: http://store.aetv.com/html/product/index.jhtml?id=75054) seems to be a History Channel production.
So, is the story ridiculous? Far fetched yes, impossible, no. Back to the plot. Nolte's character is recruited and accepts an impossibly dangerous mission and unfortunately the script does not give us an adequate reason why he accepts. Was it a type of passivity, that he got sucked into this role as it says because it was the best story he had ever written and he got to play the part? That's a hard thing to imagine any of us would grasp. But, it was an unusual time and people did extraordinary things.
The acting throughout the film by the entire cast is excellent and as people have pointed out Alan Arkin, always fantastic, is very good in a small role.
I was really shocked by the ending of the film (no - I won't spoil it) and it made me feel terrible about the choice. Did this person feel that the road was finally over and that he had spoken all that was necessary and that any more would be chapters added to a life already filled with many burnt pages? Hard to say but it really jolts.
Nolte gives one of the finest performances you can expect....the premises of the film make you wonder about a lot of things. It's very entertaining and provoking. What great movies should be. A bit long but worth it. By the way, the movie music has selections from one of the best living composers: Arvo Part.

Falsely accused, skirt-chasing chums John Wayne (as John Scott) and Eddy Chandler (as Kansas Charlie) change identities to become "Alias Smith and Jones". Mr. Wayne becomes "John Jones". Mr. Chandler's is supposed to be "Rev. Smith", but Wayne calls him "Dr. Smith". At no time are either of them as entertaining as Roger Davis, Pete Duel, Jonathan Harris, or Ben Murphy; although, Wayne can be considered infinitely more successful than any of them, career wise. Pretty blonde Mary Kornman (as Anne), grown-up from her days in "Our Gang", is a lovely interest for Wayne. She and Chandler have a couple of cute scenes with Wayne. If you're not a fan of low budget John Wayne films of the 1930s, this movie won't make you one.