Having successfully capped off Marvel's 'Phase 1' of superhero flicks with mega-hit The Avengers (2012), writer-director Joss Whedon returns to wrangle Earth's mightiest heroes, and again lives up to the massive hype. Here, he's wrapping up 'Phase 2,' while setting the table for the galactic blowout to come in the two-part Infinity War (2018). With a handful of new characters added to the first film's hefty ensemble, there is quite a bit going on, at times bewilderingly so. However, sheer spectacle, built on a script rich with humor and deep with themes of loss, ultimately wins the day.

Four distinct action set pieces illuminate the 140 minute runtime, kicked off by the team's assault on a force-fielded castle and also including a Hulk v Iron Man melee, Captain America highway chase and final, epic robot throw-down atop a floating city. Even in potentially overstimulating 3D, nearly every shot is clearly visualized and artfully framed. While no one of these thrilling sequences quite measures up to the original movie's bombastic Battle of Manhattan climax, the frequency and technical mastery of Age of Ultron's action combines to trump its predecessor's.

Across the board, the cast is in top form, even having played these roles half a dozen times in some cases. Whedon gives every character specific moments to shine, both on the battlefield and in the aftermath, where we find that each hero is haunted by a personal demon that informs their drive to aid mankind. That the movie only flags slightly when breaking down the moral implications of AI for a popcorn audience is a testament to the general buoyancy and inherent fun of the story. By simply giving us more of what worked in the first film, while smartly shuffling characters for Captain America: Civil War (2016), Ultron sets off the summer with a winking comic book bonanza.

Final Grade: A- | 92/100 | ★★★½