Jeff Lambert’s review published on Letterboxd:
Obviously it was going to be hard to top the first IRON MAN, but thanks to scribe Justin Theroux's lively script it comes close. Sam Rockwell is a great comic foil for Stark who is suddenly facing down his own mortality as the palladium core that keeps him alive goes sour on his insides. Downey manages a soulful balance between Stark's natural joviality and the slow, creeping onset of doom.
With the origin story out of the way, Stark is now paying for the sins of his father--a back story that helps establish the world of S.H.I.E.L.D. with the introduction of Scarlett Johansson's Natasha Romanoff and an expanded role for Nick Fury. The seeds of The Avengers are doled out seamlessly.
As with many a contemporary action flick, there are perhaps too many exploding machines concocted via CGI--contra Mickey Rourke, drones are not better and they remove a human element from the climactic battle. That said, Gwyneth Paltrow as Pepper Potts is perfect as ever.