Everyone hates on it because Han isn’t as much of a “scoundrel” as they had inagined when he shot Greedo and then fell in love with Leia. But those characterizations are mostly headcanon.

No, the whole point of the original trilogy's framing of Solo was that he was a terrible person who because a better person. Having him be a decent person first undermines the character growth in the same way as the retroactive change to have Greedo shoot is why people don't like that part of Solo.

I don't dislike Solo as a movie, but it didn't serve his initial characterization.