In regards to the aforementioned screenwriting decision, I have two thoughts on the matter and other details.
1.) I am happy they did not include the magical rings on the Mandarin. Having them would disrupt the aesthetic that the studio has created for its solo films; allow me to explain. Whenever I see an Iron Man film, I see it with the knowledge that I will see Stark fighting tech-based villains. Or, when I see a Thor film, I know he will be fighting magic-based foes. The focus on the-elements?powers?abilities-of this relationship effects the genre (Iron Man being science fiction, Thor, fantasy.) Disrupting this paradigm would alienate the audiences, and worse, compromise the MCU. Now, the reverse works only in special films that have team ups (a la The Avengers.) Now, don't get me wrong: I have no problem with this in comics or other film adaptations; I would geek out seeing the Hulk take on Galactus, as teased by the Wachowski Brothers. But, when I see the MCU, I have some expectations and I would hate to them have them unfulfilled.
Now, let us pretend that I am wrong, and that for some unimaginable reason, the rings are crucial to creating the definitive Iron Man film. The other problem with using them is that they would take away from the Infinity Gauntlet. The MCU has been slowly building up to an epic confrontation with Thanos. Then, audiences will see something they've never seen before - a hand accessory that can rearrange time, matter, space, and reality.
But, if the rings were introduced, they would take away from the Gauntlet...which, again, would be detrimental. What is special about being able to rearrange matter when the Mandarin has a ring that can do that (And I know, the obvious response is, well, the ring could have the gem inside it! To that, I say...no.) In the comics, the rings, as they are, work fine, but onscreen...they would be terrible. I remember a while back, a poster claimed that each of the rings served as a transponder to the Mandarin's military equipment: each of them controlled a helicopter or something. Now, if that approach had been utilized with the rings, I would be fine with their incorporation, as they would not compromise the aesthetic, genre, and franchise.
2. The "Twist"
Having not seen the film, I cannot comment on it accurately; part of me wants to say that the premise has been used before ("The Reichenbach Fall," but, as a smokescreen). On the other hand, I actually like it, as it fits into the image that Guy Pearce has constructed for himself, in film (think of the Count of Monte Cristo.)
But, playing the Devil's advocate, let's focus on the perspective of the 1% of the complaining element that has read the comics from day one and considers the Mandarin to be the best villain ever conceived (with the social baggage jettisoned, of course.) My response to these complaints is simple: deal with it.
It is not an inflammatory comment, but a truth: one I have had to learn the hard way over the years.
When I was a child, Darth Vader was one of my favorite villains. He never took crap from anybody, was an awesome cyborg, in addition to being a terrific pilot. He carried a screen presence that has rarely been replicated. However, thanks to the prequel trilogy, the character irradiated and destroyed beyond any point of repair. It started with casting the kid from Jingle All The Way (and of course, having the narrative focus on him as a kid, was stupid, as well,) and then became worse in every conceivable way. In the end, the coolest cyborg attack hound was reduced to a sniveling, child-murdering douche who made Jason Todd look like as saintly as Batman.
I did not call for a boycott of the films or wish anything negative on the resultant parties; I took comfort in the fact that the original trilogy still existed, and I could ignore the prequels. Then, the studio decided to revise the films to meet this new continuity; I was slightly upset, until the studio had the kindness to release a DVD set containing the original, untampered films.
Thus, while I do not own the series on BD (nor have any plans to, as they do not contain the original edits,) I am fine. The character still existed in one medium where he was not destroyed. Thus, the community that is upset about the decision needs to realize that the Masterworks are not going anywhere. If the spoiler is true
than be wholly destroyed as Vader was.