People had high expectation from Iron Man 3 which was coming one year after Avengers: Assemble (2012). Not only previous Tony Stark featuring movies like Iron Man 1, 2 and Avengers were a critical and commercial success and Tony Stark itself was a fan favorite(remember that this was Robert Downey Jr. at height of popularity with series like Iron Man and Sherlock Holmes), but the trailer itself looked promising. I was sold the moment trailer showed Iron Man suits being blasted. But the trailer did not stop at that. It had Ben Kingsley portraying Iron Man’s deadliest foe as Mandarin with beard and pony tail. Whenever Ben Kingsley said “You…want…see…me…coming” in the trailer, it gave literal chills. The reason I was excited was not because it was Mandarin or Ben Kingsley, but because it looked like Marvel Cinematic Universe finally had a good antagonist in their movie. You see ever since Marvel Cinematic Universe debuted in 2008 with Iron Man, a lot of Marvel Fan boys preferred Marvel Cinematic Universe because unlike The Dark Knight trilogy, Marvel movies did not take itself seriously. Their argument was that why take yourself seriously if you 40-plus wearing spandex and jumping? However no one could deny that while The Dark Knight Trilogy (2005-2012) had well written character especially the Joker portrayed by Heath Ledger, MCU rather had one-dimensional character who were rather punching bags for Superheroes ( except Loki of course) . The punching bag statement holds true for Whiplash in Iron Man 2 especially. This time, Mandarin looked like a villain threatening enough for death of Tony Stark or his loved ones. When you have a living legend like Ben Kingsley portraying a villain, you really expect something like level of Heath Leadger portrayal of Joker.
Another thing which was exciting about movie was the fact that it was first movie after the events of Avengers. Which meant that Iron Man along with Thor and Captain were full-fledged part of S.H.I.E.L.D.( Strategic Homeland Intervention, Enforcement and Logistics Division)(a secret organization lead by Nick Fury, who is played by Samuel Jackson) now. Which meant Tony Stark was no longer lone-wolf anti-government guy of Iron Man but a team member who worked for government now. It was interesting to see if supervillains were now more afraid of superheroes joining together or not? Will citizens feel safer or not? Will superheroes call each other for backup or not? Those were few of the questions at that time?
Since the director of the movie was different (previous one had Jon Favreau of Elf fame as director, this one had Shane Black, veteran screen writer of Lethal Weapon and Predator as director), the storytelling was different too. For some reason Shane Black made Iron Man 3 serious in tone in comparison to previous ones(even though Tony Stark was still at his funniest best). Also the movie was very experimental in storytelling, not just for a superhero movie, but for action movie in general. It took risk you would not imagine. In that way it was gem to watch. If I talk more I would spoil the movie. Just remember to look at similarity with The Incredibles(2004) and The Dark Knight Rises(2012)