These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Kieron Gillen's run. The first arc was generally well liked, while the second arc, while mostly liked, irked some of the fans who sided with the Avengers during Avengers vs. X-Men due to the way it treats Tony's attack on the Phoenix. The arcs following, however, for retconning Tony's dad met aliens who may be responsible for Tony's intelligence. One party found the story interesting, the other felt the idea robbed Tony of his independence by establishing he was predisposed from birth to make his armour. The ending and subsequent arc where its revealed that he wasn't the child 451 altered, and is instead Howard Stark's adopted son, and has a secret brother named Arno, is similarly split between those who're still enjoying the run, those who were unsure about the previous story arc but are happy about this revelation and subsequent possible stories, and those who just hate the changes going on and refuse to read.
Complete Monster: After seeing his father shoot himself in front of him as a child, Obadiah Stane believed two things: the first was that life was a game you cannot lose by any means necessary. The second was his father was a worthless loser who had lost. During a childhood chess match, when paired against a boy who was his equal or better, Stane slit the boy's pet dog's throat to make sure his mind wasn't on the game. Stane became a Corrupt Corporate Executive who defeated Tony Stark in a corporate buyout, reducing Tony to living on the streets as a homeless, alcoholic vagrant. When Tony returned as Iron Man, Stane wasted no time in kidnapping his friends and loved ones, showing willingness to brainwash one of Tony's lovers to be his woman to drive in the victory more. Stane set off a bomb at the Circuit Dome to kill Tony with no compunction about collateral damage. When Tony arrived to confront him, Stane revealed he'd set up a chamber with Tony's loved ones subject to receiving electric shocks should he take a step to free them, intending to force Tony to starve to death in the room. When Tony beat Stane's game, Stane played his last trump: Tony would surrender or Stane would use his own suit to crush a baby's skull. Once beaten, Stane opted to hurt Tony and deny him victory the only way he could: suicide.
Tony's had a few but one of note is the entirety of Iron Man (vol. 1) #200 where he reclaims the Iron Man mantle, faces off against Obadiah Stane, out-gambits him at every turn and leads to Stane committing suicide out of sheer frustration.
In Iron Man (vol. 1) #293-294, as part of the Infinity Crusade story arc, Tony's confronted with the Goddess, a female cosmic being who wants to "purify" the universe of evil; she wields several Cosmic Containment Units, basically omnipotent plot devices which make her all-powerful. She's trying to bring over superheroes to her cause and one of them is Iron Man. Twice, both times completely at her mercy with his naked spiritual form like a shrimp in her fist, he tells her she is a presumptuous hypocrite and no thanks, he won't join her.
Iron Man's victory over the Mandarin in Iron Man: Director of S.H.I.E.L.D. #28. Forced to wear an irremovable power-dampener to shut off his Extremis abilities, and racing against time to prevent the Mandarin from releasing an airborne form of Extremis (which will kill 97.5% of the world's population), Tony dons an outmoded armor, tracks down his old nemesis, and engages him in a particularly brutal slugfest, during which he yanks half of the Mandarin's power rings (which were fused into his spine) right out of his body, whilst sustaining a broken arm and a dent kicked in his helmet. He then downs the Mandarin temporarily with his own weapons and the Mandarin's own rings, then deliberately severs part of his own foot to get the power dampener off, fights through the pain and shock and the sensory overload of his Extremis abilities returning, then averts the Extremis outbreak. The Mandarin then gets up again and punctures a container of Extremis, prompting Tony to freeze him AND the Extremis with freon spray. Only then does he pass out. Damn...
Dork Age: Civil War and the aftermath. See Strawman Political, below. Before Civil War, there was his Face-Heel Turn during the terrible "Crossing" storyline that led into Teen Tony and Heroes Reborn. Thankfully, much of that was retconned out in Avengers Forever.
The Iron Nose. It was hated so much that the comic had fans at a convention wearing armor replicas without the nose and telling Tony Stark how hideous it looked.
Ensemble Darkhorse: Maria Hill gained a number of fans during the post Secret Invasion storylines, possibly due to Matt Fraction being the first writer to develop her outside of a role as a person to be an enemy for the Avengers.
Epileptic Trees: Immediately following Civil War, Tony is fighting Mole Man creatures with his Avengers team when, all of a sudden, Ultron reveals it has invaded his biology and transforms Tony into a copy of the Wasp. Considering Tony's biggest crime during Civil War was building a cyborg with the power of Thor (as well as locking up heroes and building a giant ersatz Masters of Evil which Ultron used to lead), it's not so hard to just assume that a lot of Tony's immoral actions were the product of Ultron inside of him, influencing his actions.
Hilarious in Hindsight: In issue 9 of Marvel Team Up, Spider-Man referred Iron Man as Sherlock Holmes, guess who plays both Iron Man and Sherlock Holmes in the movies.
Ho Yay: Piles, both with War Machine in the Iron Man books, and Steve Rogers in The Avengers.
Jerkass Woobie: Stan Lee has stated that this was his original intention in the creation of Tony Stark. He wanted to create a character who was a bit of a bastard for his war-profiteering, womanizing, and fast lifestyle but was also pitied (especially by women) for his insecurities due to his injury and the knowledge that what he was making was killing people.
Magnificent Bastard: The Mandarin has been one since the 1960s. There's also Stark himself, depending on the writer.
Moral Event Horizon: A fair few readers are convinced Tony himself came precariously close to this line in the much-maligned Civil War: Front Line, in which it's revealed that one of the ideas he had for uniting the warring superhumans was to stage a False Flag Operation to bait Atlantis into going to war with the U.S., a threat which all the heroes would have to team up against. Stark is saved from the pit by the fact that the idea remains precisely that, an idea, but had he actually gone and done it, there's little doubt most fans and quite possibly many writers would've considered him an unrepentant villain. What's worse is that the writer, Paul Jenkins (who has since become one of the most despised men at Marvel) seemed to be arguing that this was a logical thing to do!
Tony and Reed cloning Thor. Particularly as Tony was close friends with Thor, and Tony was been in possession of the hair used to clone Thor since they met.
Sasha Hammer hits this during Iron Man's Fear Itself tie-in: not only she blows off the main pilot of her Detroit Steel fleet be turned to stone by Mokk (Grey Gargoyle), she also goes on to leave Rescue (Pepper) to fight him alone while trying to make herself look good. And when he's got Pepper in his clutches and is ready to deal the killing blow, she simply... retreats.
My Real Daddy: David Michelinie and Bob Layton in the early 1980s transformed the character with such innovations such as his specialized armors and his drinking problem.
Nightmare Fuel: Near the conclusion of the Extremis story arc, Tony battled the bio-super-soldier Mallen for the second time... and this time, he won. Unfortunately, Mallen made it abundantly clear that only death would stop him... and after Iron Man has blasted a fist-sized hole through his chest and he just keeps trying to choke Tony through the armor, he repulsors Mallen's head off. And then, for a moment, Mallen's decapitated body tries to get up again.
During Fear Itself, Iron Man deployed to Paris, France, to take on the Grey Gargoyle, who was possessed by the spirit of Mokk, one of the generals of the Big Bad. There, he discovers that all people in the city have been turned to stone. During his battle with Mokk, he gets knocked out, and comes to in a giant pile of broken statues - oops, make that a giant pile of petrified corpses.
Issue 255 - Freak Quincy, after accidentally swapping Iron Man's and Crimson Dynamo's minds, getting his arms blasted off by Iron Man's pulse bolts, due to Dynamo's unfamiliarity with Iron Man's weapons systems. Quincy somehow managed to survive long enough to facilitate a reversal of the swap.
They Wasted a Perfectly Good Plot: As discussed in the Strawman Political section, they could have had an interesting plot in which Tony is forced to go to more and more extreme measures to enforce an act that would hold responsibility over all other things. Something, he believes in due to his own shortcomings. Instead, they decided in some books to turn Tony into a power hungry fascist and decided accountability = slavery. Also he's a war criminal now... yeah, apparently believing in responsibility is akin to amorality.
Complete Monster: Despite appearing in only one episode, Dark Aegis outstripped any other villain in sheer monstrosity. A foe of Tony Stark who'd been hurled out into space, Dark Aegis later wiped out an entire planet and showed no remorse for it whatsoever. Dark Aegis later attempts to use a superweapon to destroy a moon, and then attempts to destroy a sun as well. His attitude towards what this will do to an inhabited solar system amounts to: "So what?"
According to associate producer Jeremy Latcham, various writers passed on the film during both pre-production and requests for rewrites. All regretted once Iron Man was released.
Author's Saving Throw: The Mark VI's triangular arc reactor wasn't very well received, Joss Whedon himself declaring that it sucked. Thus the following iterations of the armor returned to a circular chestplate, and the triangle within the arc reactor itself was dimmed so it looked shaped like a circle again.
Awesome Ego: Tony, just as in the comics. "I've successfully privatized world peace" is such an audacious and narcissistic thing to claim, but not only is it partially true, he's just so awesome for daring to say it.
Awesome Music: The movie has a traditional score soundtrack, it also has a licensed soundtrack that contains nothing but best of AC/DC songs used in the film one way or another.
Actually, there are only two AC/DC songs used in the second movie, plus one in the first and maybe three others in advertisements for the film.
While the film has a serviceably action-movie score, there's a surprising track of very reverent music when Rhodes arrives at Edwards AFB in what will become the War Machine suit. Seriously, it sounds like the soundtrack for Jesus discovering the Grand Canyon or something.
Ensemble Darkhorse: Dummy, from the first film. Sure, it's an artificially living thing but it has its fans.
Genius Bonus: The Vanity Fair reporter at the beginning of the film refers to Tony being nicknamed "The Merchant of Death." That's actually the phrase used in the obituary for Alfred Nobel, inventor of dynamite, which was accidentally published before his actual death, and was what inspired Nobel to use his fortune to create the Nobel prizes for people, so as to try and make the world better. Kind of what happens to Tony during the events of the movie.
A newscast in the first film mentions rumors that Tony is suffering from PTSD following his return from Afghanistan and has been bedridden. Come the third film he is suffering from PTSD following The Avengers, and he hasn't been able to sleep due to nightmares.
Marty Stu: Subverted. On the surface, Tony Stark is a textbook example: he is, at the same time, incredibly smart, handsome, muscular, and rich. He rides cool cars, gets lots of poon, and, when the times is right, can easily kick evildoer butt. However, unlike bona fide Marty Stus, he has huge personality flaws (like being a dick even to the closest friends), health issues, and his flaws end up damaging his friendships and public image in the second film, which make him a much more believable and likeable character.
Narm: Tony talking about "the mission" in the first movie is supposed to emphasize his determination to ridding the world of his illegally sold weapons but it comes off as very out of place (making him sound like a shell-shocked soldier of fortune, which doesn't line up with pretty much anything about his character; even if he was being more serious than usual it doesn't feel like something someone like him would say).
What Do You Mean, It's Not Political?: With Tony taking the fight to Middle-Eastern terrorists in the first film and refusing to hand his property over to the government in the second, there are some who see him as the ultimate conservative/Republican/Libertarian/Objectivist super hero. Which actually makes sense, considering that Stan Lee has talked about how he enjoyed the idea of creating a character like Tony Stark in the middle of The Sixties, saying that he wanted to create "the quintessential capitalist," explore Cold War themes, and that "I think I gave myself a dare. It was the height of the Cold War. The readers, the young readers, if there was one thing they hated, it was war, it was the military....So I got a hero who represented that to the hundredth degree. He was a weapons manufacturer, he was providing weapons for the Army, he was rich, he was an industrialist....I thought it would be fun to take the kind of character that nobody would like, none of our readers would like, and shove him down their throats and make them like him....And he became very popular."