Casting such an accomplished mix of actors was brilliant. I'm sure George Clooney had some pull, and the result was fun and witty. Aside from longtime acting pals, Clooney and Matt Damon, there were veterans Bill Murray (who recently played FDR in another similar-era movie) and "Roseanne" husband, John Goodman. The Earl of Downton Abbey, Hugh Bonneville, did a spiffy job, as did Jean Dujardin (from "The Artist"); his 007-ish spy roles in the French versions of James Bond came in handy.
Sadly, both "foreigners" died. Bob Balaban and Cate Blanchett rounded out great supporting allies. I wish movie studios would produce "blooper clips" and "behind-the-scenes" clips involving such a cast of characters! Other stories I'd love to hear are the antics and working relationships that they all had, once each day's filming was done.
This film has everything that a classic WWII movie should: an amalgamated group of Allies (brought together in similar style as Clooney did in Ocean's Eleven), sinister villains (stone-faced Nazis, a bloated Goebbels, and a Hitler-look-alike art thief Nazi officer). It also had a snappy reoccurring theme-song--incorporating whistling marches and drum cadences. The plot involved hidden treasure, coded maps, a castle, church relics, a beach landing at Normandy, military convoys, hospitality from European anti-Nazi Resistance, a Nazi Mercedes touring car (replete with flag holders on the fenders and a sidecar-motorcycle escort), the arrest of a disguised Nazi, a hijacking, a race against the Russians, and random acts of kindness to harmless Germans "who probably didn't know any better". Not to mention a touching wartime Christmas scene--thinking of the loved ones back home overseas and dreaming of a white Christmas. 
Yet, it also captured the adventure that many American "doughboy" soldiers probably experienced in the European "war theater"--despite the threat of death--as they drove convoy columns of Jeeps across Europe's grandest countryside, or as they flew in cavalier fashion over Parisian rooftops… tasting French cheese, Austrian coffee, Italian sauce, Belgian chocolate, or German gingerbread during the trip. (To be sure, every war or crusade brings back new flavors from travelled lands).
Considering it was the early 1940s, travel was much more lenient: no "blocked flying zones" above cities, the free ability to fly or drive over random parts of the country, and open roads that skirted mountains and pastures. Yes, ALL of that was captured on film and represented beautifully to the audience. Best of all, it's based on a true story! (Below)
The movie doesn't focus on the tremendous technological and scientific advancements, inventions and research accomplished during WWII. In fact, its focus is on preserving "the past". Scenes involve rural countryside, Paris café society, church tradition, and academia.
The delightful (sometimes suspenseful/sometimes fun) soundtrack was created by Alexandre Desplat!
Watch this movie. An enjoyable mix of whimsy, national pride, tragedy, teamwork, and "old friends coming together" camaraderie!
