The inevitable sequel to the 2008 smash proves once again the perfect fit between actor and character as Robert Downey Jr. plays the title role with his rakish wit and deep sense of irony fully intact from the first film. Sharply directed once again by actor Jon Favreau and shrewdly written by another actor, Justin Theroux, the 2010 blockbuster is as much an actors' showcase as it is a special effects-saturated comic book adventure. This precarious balance is what made the first film so ideal, and while the surprise element has been replaced in part by a breezy familiarity in the sequel, the result is still far more entertaining than most in its genre. This is despite the fact that the movie is overpopulated with colorful characters, most worthy of a film of their own.

Overkill is a common problem in heavily invested Hollywood studio product like this, and one can quibble that nobody except Downey gets sufficient screen time to make a compelling impression. As hedonistic billionaire Tony Stark, the actor has to face off with no less than three villains, two figures who are intentionally put on a nebulous fence between good and evil, the mysterious director of a clandestine organization called S.H.I.E.L.D. and a love interest designed to be either a sharp, take-charge businesswoman or a helpless damsel in distress depending on the plot machinations. The story picks up Stark six months after the ending of the first film as he boasts to a rapt audience at the re-instituted Stark Expo how he has maintained world peace with his impenetrable suit of armor. However, underneath his hubris, Stark hides the fact that he is dying from poisoning by the palladium core in the arc reactor that gives him not only his unique powers but his re-born life.

Meanwhile, taciturn, cockatoo-loving Russian physicist Ivan Vanko is plotting revenge against Stark for the act of betrayal he feels Stark's father committed against his dying arms-dealer father. In fact, Vanko has designed his own arc reactor with the intent of destroying Stark, an act almost realized at the Circuit de Monaco. Stark's smarmy business rival, fellow weapons manufacturer Justin Hammer, will stop at nothing to secure the secret to Stark's armored suit, while U.S. Senator Stern of Pennsylvania wants Stark prosecuted for crimes against the state. On the fence about Stark is a carryover from the first storyline, Lt. Colonel James "Rhodey" Rhodes, whose friendship with the billionaire is severely tested by Stark's excessively destructive behavior. A new character, Natalie Rushman, is introduced in an ambivalent manner as a new assistant to replace Pepper Potts, Stark's feisty gal Friday-turned-CEO. Natalie's motivations are revealed in due time. It all comes to a head at the expo where Vanko and Hammer have colluded to produce an aerial battle royale.

That's a whole lot of plot to fit into a 124-minute movie, but at least the momentum never flags. The problem for comic fanboys may well be the dearth of action sequences. The showdowns between Stark and Vanko create the necessary tension although the build-ups are rather predictable, and the climactic battle sequence feels more like a swirling meteor shower since it takes place at night. Still, cinematographer Matthew Libatique and art director J. Michael Riva do first-rate work here with the production details. Moreover, the actors do their best even if their characters are given short shrift in the screenplay. Mickey Rourke relies on his own uncomfortably maniacal screen persona and idiosyncratic touches to embody Vanko's two-dimensional motives, while Sam Rockwell is even more cartoonish with a petulant, hammy albeit amusing turn as Hammer.

Replacing Terrence Howard, Don Cheadle does what he can as the put-upon best friend and archetypal soldier, but Rhodey has to represent the film's most thankless role. A surprisingly cast Garry Shandling brings a nice edge to the avuncular senator, and Favreau himself repeats his role as Stark's loyal chauffeur Happy Hogan. No fool as a director, he gets to face off to primarily comic effect with Scarlett Johansson, properly feline and physically adroit in her black catsuit, as Natalie. Her ball-breaking "Charlie's Angels"-style fight sequence is entertaining if a bit derivative. As Pepper, Gwyneth Paltrow gets more to do this time around, bantering with Downey with Nick-and-Nora-level élan, but the character is near-impossible to believe. Fans, however, will have no problem loving and believing in the sequel, but the pervasive one-liners and the wild zigzags between hubris and insecurity make a strong case to redub the hero Irony Man.