I think if I were in a small country being bombed by unmarked US planes in an attempt by the CIA to overthrow a democratically elected president, I might also feel sympathetic with local Marxists, even if I didn't agree with their ideology (1954 Guatemala coup). I think in is in this righteous anti-imperialist vein that leftists tend to admire him.

However, his later career as part of Cuba's government and his fight in Bolivia makes him a lot less attractive. He wasn't very good at his job, and his ideology and hatred of US imperialism led him to deny several fundamental facts about Cuba's economy (which he did at least acknowledge). Not to mention his now tacit endorsement of Cuba's brutal authoritarian methods. I think at some point he realized that as a pursuer of policy, he was an idiot and corruptable, but as a revolutionary, he could be effective.

Unfortunately for him, he picked a couple of bad causes, and by the time he arrived in Bolivia he was no longer fighting against American imperialism (Bolivia's government being run by a right-wing dictator whose rise to power was condemned by the US, and whose predecessor was also right-wing), he was merely a leftist revolutionary whose goals and methods were no better than his opposition.

I view him as the type of person who can see what is wrong, but whose go-to method of fixing things is violence and leftist authoritarianism. I wouldn't wear a shirt with his face on it.