From what I know, much of the Chauchat's bad reputation stems from the American M1918 version. It combined the original design weaknesses with a production flaw - the barrel was not correctly converted for the American caliber and thus often jammed even in new and clean condition. In addition I think the US version only had a magazine capacity of 15 rounds.
Also I could imagine that soldiers were prejudiced against their new job for other reasons. The original 2-men teams were completely overloaded. The first gunner was to carry the Chauchat (20 pounds), 16 magazines and a pistol with four extra magazines. The second gunner was to carry an infantry rifle, a shovel and 900 rounds of ammo - besides their other personal equipment. Imagine that someone tells you to wobble over the battlefield packed like that, and to shoot an an entrenched enemy from the hip. At least that was the official instructions, I don't know whether this hip-shooting was ever used in actual battle.
The kick in their face that soldiers often received by the rear part of the gun was dubbed "la gifle" in french and evidently could be quite painful. The German soldier posing with the gun is holding it the wrong way because the bushing would recoil against his cheekbone. You had to be careful to put your cheek in front of that part to prevent injury.
