I'm a big Marvel fan but not a fanboy. There's a difference. When something is terrible, I'll admit it. But upon re-watching the entire MCU over the last few weeks, I noticed that some of the internet assumptions are flat out wrong. For example, Ironman 2 and 3 are not bad films; far from it. If you want to read on, I'll defend especially IM2 but also IM3.
I'll grant they're not great films, but to say they’re bad is to put them in the Fantastic Four or Green Lantern level. They're not even close to this. But IM2 has a lot going for it as it starts to build the MCU and introduces and develops a whole lot of characters. We have the nicely placed intro of SHIELD and Nick Fury and The Black Widow. We have further development of War Machine in a big way. We have the beginnings of the government concern over Superheroes and the threat of Stark technology proliferating around the world. Yes the villains of Whiplash and Justin Hammer were a bit weak, but not bad. Marvel doesn't need to emphasize the villains. I finally accepted that MCU villains are just a stepping stone for the heroes. The emphasis is usually on the characters' internal and relational problems to overcome.
The glue that holds IM2 together and makes it work well is Stark's clear understanding that he's dying slowly of poisoning. To overcome this problem, with the help of Fury, he cracks the mystery of a new ARC reactor not based upon the poisonous Palladium but on clues left by his long-decease father. Stark eventually creates a new element. In the end, with help from Rhodey, he beats the drone-bots and Whiplash. He seems to be doing better at the end of the film with a new formal relationship to SHIELD and romance with Pepper. Does the plot of IM2 have some holes? Of course, all movies, especially CB ones do. But the holes are reasonable imo. The character of Tony Stark and Ironman are perhaps the most feasible compared to other CB heroes-- a rich guy with psychological issues in a high-tech mech suit.
If you watch IM1 through IM3 in succession, it flows nicely. IM2 picks up directly after the last scene of IM1 where Stark says, "I am Ironman." The Ironman trilogy works precisely because of the Stark character development-- a guy who has incredible wealth, power, knowledge, but who becomes even more self-centered, insecure, paranoid and even prone to panic attacks by IM3. With a quick narration intro by RDJ himself, IM3 starts out great especially with the initial threat of The Mandarin. The complaints about IM3 come down to the bait and switch of the real Mandarin for an imposter; the one dimensional character of the villain Killian and his cohorts; and Pepper Potts mutating into the OP savior at the end with the Extremis injection. I admit that these are problematic for the plot, but not a deal breaker for me.
The plot still holds together and flows well if you look at it from the perspective of Tony Stark trying to solve the mystery of the Mandarin and take him down. The action sequences are fantastic-- saving a bunch of people falling out of bombed plane, and the ending with all of the fast motion of the robotic Ironman suits as Stark and Rhodey (Iron Patriot) save the President of the United States. At the end, Stark gets his head and heart (literally) together and start living a life with less fear and reliance on his artificial Ironman suits after he blows, presumably, most of them up. When it's all said and done, I challenge all you naysayers to give the Ironman trilogy another shot. It's not bad but good, if not even great.