Mélenchon is... frustrating.

He's the main contender on the limited field of the actual left in France. He's got a lot of proposals that are actually good and desirable.

He's also a narcissist and a populist whose stated approach to achieving his proposals is to denounce treaties he doesn't like and somehow force other countries to replace clauses with whatever it is he wants.

He's also incapable of compromises, and right now busily torpedoeing the left wing alliance that won the election because his own party didn't win enough seats to take charge of the alliance.

What I don't know is, how much of the populist/anti-system talk is just talk for political reasons, and whether he would in fact be capable of the nuance required to govern. He might. He might not. He's clearly smart and charismatic. But he's also the type to huff his own farts hard enough to mistake the visions for the truth of the world. So... In that respect, pretty much just like Macron.

France has a big, big problem with overemphasizing individual politicians over policies.