So he is a nutty leftist, just not a nutty far-leftist?
Basically. When you know actual French far-leftists, you can easily see the difference.
Yes but France is several notches to the left of almost every other developed western nation with the exception of the Scandinavian states. Although the difference is their political discourse seems competent, whereas in France it seems like half of their politicians are still stuck in the 1790's. Melenchon would be considered a far-leftist outside of France. Even the BBC, a bastion of liberal-leftism, calls him a far-leftist, as to other such bastions like the Guardian.
They also think Syriza's far-left, so they're not exactly the best judges. And France has had 2 left-wing Presidents since the war, hardly "several notches to the left of almost every other developed western nation".
Well, to be fair, within Greece's political system SYRIZA and the KKE were the far left until this year. They were certainly quite a bit to the left of the mainstream PASOK and DIMAR. And don't use that "only 2 leftist presidents" excuse, major leftist proposals like the 35 hour work week were passed and never repealed, even with Presidents from the French Right.