I don't like Iron Man 3, but I've heard compelling arguments from people who like it as to why they do.
Iron Man 2 is just a straight up terrible movie. It's only redeeming features are the Genndy Tartakovsky storyboarded action sequences, Sam Rockwell's Justin Hammer, and Matthew Libatique's cinematography. What you're left with is an awful script full of awful characters doing a lot of nothing in as many stupid ways as possible.
I have nothing but respect for all the MCU attempts to retroactively make it seem like less of a train wreck, but they can't undo the fact that the central dilemma of the movie could have been solved in two seconds with an extension cord.
No need for Tony to invent a new element that his father had mapped to the layout of the Stark expo (god, I still can't believe somebody okayed that) or put his affairs in order because he was slowly poisoning himself.