You sure couldn't tell it was a popular gun by the number of holsters sold for it. Without revealing actual sales figures, Galco holsters for Glocks and even 1911s (not a terribly popular cop gun) outsell FiveseveN holsters by at least 50,000%.
I, for one, will contest that judgment because it conflicts with the popularity the gun is gaining in U.S. police forces. Lots of cops seem to like the reduced recoil (remember, the reason they went to .40 instead of 10mm), and greater accuracy, of the pistol.
International popularity? Because the French and Belgians are such authorities on gunfighting?
Not trying to argue, but personal feelings aside the FiveseveN, and its round, are gaining international popularity, and not without reason.