The twist with Liam Neeson's Ra's Al Ghul works because his character has a personal bond with Bruce Wayne. He taught him many things, and they both were inspired to fight crime by the loss of their loved one. But the reason why the twist works with Liam Neeson, is because Liam Neeson shows what Bruce would ultimately become if he would allow his sense of justice and order to overshadow his sense of morality and compassion. It escalates everything that movie was indicating from the beginning of the film. You saw a glimpses of Liam Neeson's methodology to fight crime being way more radical and lethal than Bruce's.
It's an emotionally complex arc that has profound thematic integrity to it.
Not to mention, Liam Neeson was actually a comic book accurate representation of the Ra's Al Ghul, minus immortality, but even that aspect was mentioned briefly in the movie. So it clearly says that Nolan, unlike Shane Black, doesn't wipe his butt with comic books.
1. Ra's Al Ghul. 2. Sensei - father of Ra's.
The problem with Mandarin twist, apart from being a completely disgraceful towards the comics, is that it feels very random and not thought-out. Movie wasn't indicating that its about the reprobation of the perception of evil in this world. The twist appears randomly, it has no complex idea behind it, and it never escalates the story into something emotionally satisfying. After the twist happens, the movie turns into a generic story about a revenge. Evil businessman guy wants to kill Tony Stark because he has some trivial gripe against Tony Stark... Never saw that before.
If this movie was actually more about drama and substance instead of superficial storytelling and dull jokes, the twist wouldn't be played out as a ******ed comedic gag. The scene would be more serious. The Trevor wouldn't be a walking-talking fartbag. He would be forced to do all those things because bad guys kidnapped his family and they forced him to act so that his family will be alive. That's already gives a much better explanation as to why someone would agree on doing something like that.
And the last act of the movie wouldn't be a random fight scene in a docks. If movie was thematically complex, the last act would play out within the theme about world and politics being ambivalent and not one-sided. Because the bad guy used a spurious frontage of a terrorist to insert fear into people and into government, which he would do through horrible terracts (with real people and not stupid concept about human bombs), the government would decide to start War on Terror, and Tony Stark had to prevent that from happening. The bad guy wouldnt even need any fire-breathing superpowers to do that. He didn't even need to have any superpowers. He would just use manipulative schemes to do that. The bad guy would manipulate U.S. troops to attack a civilians somewhere in middle-east, and Tony Stark would suit up, go there, and start fighting with the U.S. army. Rhodey would be a leader of the operation. He wouldnt be aware of the true context behind the situation, thus it would create the conflict between them both. Iron Man and War Machine have to fight for their ideals. U.S. would proclaim Iron Man to be an enemy of the united states. Tony Stark had to fight on his own against everyone.
You couldve done so much more with that. In a first film we saw Tony Stark fighting for the U.S., but now the paradigm has changed. It would thematically fit everything about the first movie (the only good IM movie), since now has to not just reconfigure his morals, but to reconfigure his perception of right and wrong. But f8ck that, right? Fire-breathing people, explosions, fart jokes, and docks are more interesting?
All in all, Iron Man 3 was a terrible, superbly superficial film for me. People mistakenly think that the only problem with the movie is the fact that it ruined the Mandarin. It is, of course, a terrible idea to make Mandarin a walking fartbag, but the movie sucks not just because of that. It has tons of other problems. I would bring Gravity as an example. Gravity is a great movie, but it's scientifically inaccurate. But people like the movie because it's emotionally satisfying. Iron Man 3 isn't comic book accurate, but it's also emotionally unsatisfying, clunky, poorly written, and joyless. If the movie was actually profound, deep, and well-written, people wouldn't hate it so much.