As "Iron Man 2" opens, Tony Stark, the wunderkind head of Stark Industries, has just revealed to the world at large that it is indeed he lurking inside the metallic suit of the planet's latest crime-fighting superhero. But such a public admission comes with a steep price. For now the United States government wants him to register himself as a deadly weapon; a rival defense contractor (Sam Rockwell) is determined to beat Stark at his own game by creating his own army of iron-clad warriors; and an arch-nemesis (Mickey Rourke) from the former Soviet Union has suddenly appeared on the scene in his own superhero getup to destroy Stark in a mano-a-mano battle on the streets of Monaco.

As a piece of pure Saturday-matinée popcorn entertainment, "Iron Man 2," directed by Jon Favreau, is, perhaps predictably, a notch or two below its dazzling 2008 predecessor. However, the sequel still has enough quality elements – most of them holdovers from the first film – to recommend seeing it: namely, Robert Downey Jr. as the wisecracking, hard-living but lovable boy genius, Stark; Gwyneth Paltrow as his endearing personal assistant, now CEO of Stark Industries, Pepper Potts; and enough funny one-liners to take the edge off of some – though not all - of the script's numerous plot contrivances. As with the previous film, Downey Jr. and Paltrow achieve a wonderful love/hate chemistry between them, and the cast has been expanded to include Don Cheadle, Scarlett Johansson, Samuel L. Jackson (who had an uncredited role in the first one), and Kate Mara as well.

The screenplay by Justin Theroux makes at least one right choice by having Stark becoming ever more gravely ill as a result of the chemical he has to keep pumping into his chest to survive in his semi-cybernetic condition. This has the effect of humanizing the character, making him destructible and vulnerable and, thus, someone whose fate we can come to care deeply about. And, needless to say, Downey Jr.'s smart, savvy performance is equally instrumental in helping us to connect with the character.

The special effects and actions scenes are impressive, of course, but it is Downey Jr. and Paltrow who once again make the movie soar.