The French poured buckets of money into the Maginot line. The Germans just went around it. The Germans had tried the same end around in WW-I (though failed), so the lack of defense at the BeNeLux border was a costly strategic mistake. Hitler had it in for France because of the Treaty of Versailles, and even went so far to track down the rail car that the Treaty in Versailles was signed in, to rub Gallic noses into. Even the new tactics could be seen on their doorstep in the Spanish Civil War. The French should have seen it coming.
I think the part of the "cheese eating surrender monkeys" comes not from the initial invasion, but the puppet government that was Vichy France. The Russians fought to the last man in horrible siege conditions for years. France started to be a puppet regime paying tribute to Hitler and rounding up Jews just a couple months after initial invasion. Only later when Hitler changed terms of the agreement did the French underground resistance really form.
That, and there were two, probably more interesting "surrenders". When the French left the colonies of Algeria and Indochina (Vietnam), there were those that saw that as surrender. I call them interesting because they didn't leave because of being defeated, but they realized that the barbarism that it would take to hold these territories would change the national character. It's hard to talk about "Liberte, Egalite, Fraternite" when you're tossing people off of helicopters or torching villages. Was this surrender? Maybe on the ground, but to win a military would entail other surrenders of character, again, an interesting trade off.
In reality (and I'm of Polish descent) the Polish fighters lasted longer. (Compared to the French) the Polish had the disadvantage of being a new country, (re)formed in 1919 after, in effect, disappearing completely for a hundred years or so. Oh yeah, and they got attacked on two fronts.
I don't begrudge any credit to the French resistance. Their fighters fought bravely. The Poles fought just as hard against two armies, with less notice and much fewer resources. I wish they got more credit. Part of the Polish jokes were real - you did have farmers on horseback with single shot rifles going against tanks. But what else are you gonna do, let them roll into Warsaw without a fight?