I'll be honest, when I first watched the Iron Man 3, learning that Ben Kingsley was just a drug addicted actorrrr was really disheartening and it was hard for me to enjoy the film after that point. I was really excited to see the real Mandarin on the big screen, I was curious as to how they'd to his 10 rings. This was just after Avengers and cosmic/magic elements had not been introduced to the MCU yet. This movie basically taught me never to go in to an MCU film with any expectations. Don't create theories and don't think that just because it's in the comics will mean it's in the films.
After many subsequent watches however, it's a really darn good film and really is a good closing chapter for the Tony Stark character. Obviously they explored his character further and he became even better but if IM3 was his final film I'd still be satisfied with his arc.
The MK42 suit was also dumb on my first viewing, totally dumb that it falls apart so easily. In retrospect it makes for some great action set pieces. The final set piece with all the suits is one of the coolest parts of the whole MCU.