First, entire story set around Christmas.
First act is A couple of flashback scenes following the opening scene of Tony crash-landing in Tennessee - first to his childhood/his mother's death, and then to meeting Hansen for the first time on New Year's Eve 2000 in Bern, Switzerland. A young Killian and Dr. Wu also appear. Hansen discusses her idea that was to become Extremis, and Tony suggested a solution to a glitch in the concept (something which will be brought up again).
First "appearance" of Mandarin is when Tony is disabling his Stark Industries mines in Afghanistan while the US forces are tying to take down Ten Rings Snipers and acquire some vaoult - which turns out to be a makeshift cinema which plays a message from the Mandarin.
Rhodey becomes Iron Patriot, Tony starts having panic attacks, shows off the XLII. The suit can be remotely controlled (the still where the suit is on that sofa; the suit is empty, Tony is controlling it from his workshop). Killian meets with Pepper to propose a partnership with AIM. That night, while Tony was having a nightmare, Pepper tries to wake hm up and the suit assembles on top of her restraining her (that bit from the first trailer) and the Tony orders it to shut down and drags it out of the room.
Grauman's Chinese Theater - Killian's two lackeys - Taggart and Savin meet while Happy spies on them in the distance. Taggart takes the Extremis virus (it is vaporised in an inhaler) and blows the theatre courtyard up - Happy is seriously injured.
Next day - after Stark visits Happy in hospital, there's the scene with the paparazzi and Stark issuing a threat to Mandarin with his home address. Then, of course, Maya visits him at the mansion, then the helicopters attack.
Cue the 20 minutes of footage that you can read about from IGN and other sources (heli attack, crash landing in Tennessee, Stark meeting that kid Harley)
Tony leaves voicemail for Pepper to not trust anyone even Maya, into the broken suit helmet at the destroyed mansion (that scene from trailers/official still/character poster). She meets up with Maya.
Back in Tennessee, Tony finds out that Harley's dad was an officer who 'blew himself up' (the bit from the trailers with Tony and the kid at the wrecks of the explosion with body-shaped shadows), turns out he was an unsuccessful Extremis test subject. Agent Brandt (Szostak) and Savin, posing as FBI find Tony at a bar, but Tony summons a repulsor from his broken down/in repair XLII to fight back. The two escape with Killian. After Jarvis repairs himself, he gets in touch with Stark about the location of where Mandarin's videos were shot - a mansion in Miami.
Pepper gets captured by Killian while with Maya, and Brandt captures Stark while he tries to attack the Mandarin. Rhodey is captured as well and his IP suit taken by Savin at AIM HQ after receiving a distress call. All three taken to basement lab at AIM. Killian/Maya demand the formula that Stark suggested to Hansen in '99. Stark refuses, and summons his now-repaired suit. Killian kills Maya and escapes, Stark gets Rhodey out. Stark heads to Air Force One to stop Taggert who wears the Iron Patriot suit, while Rhodey heads to the oil tanker/docks in Miami (overheard plan). And Tony opens the "wine cellar" - the 40-odd Iron Man suits (Heartbreaker is NOT mentioned) all launch up and head towards the docks.
On AF1, Savin traps the President in the Iron Patriot suit and autopilots him to the docks. Mandarin releases Christmas video. Cue final battle at docks, Pepper and the POTUS saved, Mandarin and Killian still at large.
Some of the descriptions in the novelisation sound quite underwhelming I have to say, hope there's more in the film.