I thought Killian was the perfect twist villain (and this is going to get somewhat political, but you know what? So does the movie. I'm just analyzing it.) and does a wonderful job of showing how racist the War on Terrorism really is.

Let's look at Slattery's parts of Iron Man. We see that he is Southwest Asian (Middle Eastern but a less Eurocentric term), likely Arab, and taking credit for several terrorist attacks. We believe it unquestioningly, and are genuinely terrified of him as a villain. He "attacks" Tony, "nearly kills" Happy, there's a lot to be afraid of with this guy, and nobody questions his identity. Nobody stops to think "What if it's not him?" Yes, the comics are a part of it, but that's out-of-universe. In-universe, the characters don't question it, so neither does the audience.

Then there's the scene where Tony finally meets Slattery, and he reveals himself to be a comedic actor, being paid good money to impersonate the Mandarin. Killian, a very white man, is out there and was behind the near-deaths of Happy and Tony, as his pursuit of science to help veterans is getting people killed. The audience is suddenly forced to question everything they know. What? Killian was the terrorist and not Slattery? Not only is it a great subversion, but also statistically backed according to Federal sources, saying that white people are a bigger terrorist threat in the US overall. Slattery was the perfect character to do that with, and it's handled brilliantly throughout the movie. People accused the movie of whitewashing, but they actually kind of did the opposite, debunking a racist stereotype.

Greatly handled with a wonderful personality (highlighted in All Hail the King). I truly hope that that cliffhanger gets resolved in Shang-Chi. The dream is for the movie to open with a shadowy figure (the Mandarin) ordering Slattery's execution, watching him get offed, and then he steps out of the shadows to reveal what he looks like, cut to however many years later. Although I'm not sure how likely they are to go through that.

@Brett3801 agreed (to an extent)! I used to be a big critic of the Mandarin twist, but looking back on it, I have a much greater appreciation for it.

My biggest reasons for hating it used to be “it’s not comic accurate” and “Iron Man doesn’t get to fight the Mandarin”. But thankfully, I’ve been able to see the bigger picture, and liberties need to be taken with these stories if we are to receive thematically thoughtful content.

Of course, Iron Man moved away from fighting for his personal/corporate interests towards fighting for all humanity, so the Mandarin would not have been an appropriate villain for him. But more importantly, the twist offered that commentary on the War on Terror that we all needed but didn’t want to hear.

I think this same story was tried with Obadiah Stane, but the Mandarin version was arguably much more effective. Both represented parts of the military-industrial complex perpetually setting up wars in order to profit, but Stane represented a cog in the machine while Killian / Slattery represented the “masterminds” who create the targets, send men to die, and reap the rewards.

Absolutely. And the way they even played the audience like that. How many other Marvel movies are willing to give such an uncomfortable truth? Sure Vulture talks about how the rich suck in Homecoming, but that's the villain saying it. This is the hero and the audience learning this somewhat uncomfortable truth at the same time and it is handled so well.

I never understood all the hate about the Mandarin twist. I thought it was a great, unexpected twist. I do hope we see the REAL Mandarin at some point, but I liked this fake version! He served the story well.

We will see the real Mandarin, he's already confirmed to be in Shang-Chi (although they'll need serious makeup work on the actor to make him live up to the hype)

Why does he need makeup?

I don't know, he's just not what I imagined the Mandarin looking like after all of the build-up he's gotten as this ancient thing who controls a shadowy terrorist organization. He looks more like he belongs on the Bachelor.

Ok, not the Bachelor, but the point is he looks too soft and not how I imagined at all

This is what the Mandarin looks like

In the comics, sure, but in the MCU they've built him up so long that the guy they picked on his own, is still slightly disappointing. I don't know, but that's just his looks. It definitely won't affect my opinion on the character at all.