This kind of felt like Shane Black and Marvel had a lot of ideas for an Iron Man movie and tried to throw them all in this one film. I never really got invested in the film because it was one loose thread after another with a fairly vague endgame for most of the film.
Also, the tone was all over the place. Tony's PTSD went from serious issue to a gimmick for funny moments with the kid. While I liked the stuff with the kid, the whole thing felt bizarre and almost like it should have been in a different movie altogether. And while I know we love Tony Stark and his devil may care attitude but a little sense of urgency would have been nice.

As others have mentioned, Rebecca Hall didn't really need to be in the film and I personally felt like she was all over the place. When the twist occurs, she seems like she's all in but then later she suddenly has serious regrets. One talk with Tony Stark changed all of that?

The Extremis powers were never defined and seemed to change to fit whatever was needed.

"The File" and the meeting with the mom were laughably convenient yet still nonsensical.

The master plan was also pretty weak. An interesting film could have been made with War Machine getting used as a pawn to stir up anti-American sentiment by attacking incorrect targets based off bad info but nothing really came of this part at all.

And where the hell was S.H.I.E.L.D? Tony Stark is presumed dead and they are nowhere to be found? Wasn't one part of The Avengers that they became a team yet they seem to have no qualms with an active terrorist who then also kills one of their members?

All in all, I was entertained but underwhelmed.