"The Great Escape" is an engrossing, well-acted, and fairly accurate portrayal of the famous escape of some 76 Allied POWs from a German Stalag during World War II. You get to see the intricate detail of the escape operation--and you also get to witness its bittersweet aftermath.
Good, often understated, ensemble acting by what was for the 1960's an all-star cast, adds further to the sense of realism. In particular, Donald Pleasance poignantly plays a POW who gives his all to make the mass escape succeed, but then realizes he can't go himself because he's going blind.
But "The Great Escape" is more than just an exciting adventure story. It also reminds us of several important things about the human condition: Human beings need to be free, as much as they need food and water. And they will struggle against enormous odds to gain their freedom. But freedom never comes cheap. The Allied POWs succeed in breaking out of the Stalag and dashing across Germany, in hopes of reaching a neutral country. But, as it turns out, at a very high price.