This week at the movies brings just one wide release: Iron Man 2, the hotly-anticipated superhero romp starring Robert Downey Jr., Don Cheadle, and Scarlett Johansson. What do the critics have to say? As with many blockbuster sequels, Iron Man 2 is bigger, louder, and filled with more characters than its predecessor. Critics say that doesn't mean it's better, but it's still got enough firepower to kick off the summer in fine style -- and the always-delightful presence of Robert Downey Jr. ensures that Iron Man 2 stays on track.