Well, I enjoyed it very much. From the tone and continuity that Shane Black brought, to the character depth and motivation, it works very well within the "Marvel" mythology. While I really liked Ben Kingsley's performance, I wish that the twist hadn't been placed in there - it would've been cooler, in my opinion, to see him either play the villain just straightforward the way he thought he was originally going to when he signed on to do the film in the first place, or to have the Mandarin partially motivated by a pact made with Aldrich instead. But, such is life, and all of the performances were golden to me so I haven't got a single complaint to make there.
I'm glad that everyone in the cast got a chance to shine (Cheadle in the Iron Patriot suit, Paltrow when infected with Extremis) and that we got a chance to see Tony Stark from a new and different perspective, as demonstrated in the infiltration scene of Trevor's mansion - but most importantly: I liked that the ending played out as an old-school Initiative Ending (or False Ending); it's a basic but rarely used Film School tactic which is employed to signify a possible scenario that could potentially play out as an all-out final ending for a saga whereas the audience knows there's absolutely or probably very much more to come about somewhere down the line, as is the case here given the real-world workings of contracts and monetary incentives to keeping such a fruitful franchise alive despite the consequences set throughout the story. The other best example of that tactic's employment which automatically comes to mind would be in the fifth season finale of "Supernatural" entitled 'Swan Song'.
While never intended to out-perform the coveted and monumental first superhero crossover film that was "The Avengers," as with the "Men in Black" trilogy: This threequel ranks somewhere below the original installment of it's solo series yet directly above it's immediate predecessor in the form of "Iron Man 2". Outside of a few personal nitpicks of mine like having yet another one of Iron Man's villains get taken out in an anti-climactic and unfashionable manner, or the needless disposal of Rebecca Hall's character, or the convoluted twist concerning the Mandarin (as spoken about above), Shane Black's book-end to the trilogy that Jon Favreau successfully began only half a decade ago, has proven that sometimes - not very often in the film industry, mind you - but sometimes: Three times truly can be the charm.
Rating: 3 1/2 of 4