In secret Iron Man (Robert Downey Jr) is building Ultron, a machine designed to protect the Earth from the extraterrestrial forces of evil leaving humans as the only threat to Earth. However, it doesn't go to plan, with some sort of delusion Ultron (James Spader) decides that the biggest threat to peace are the Avengers themselves and well...lots of stuff happens.
Back in 2012 Joss Whedon managed to gather the main Avengers onto one screen, fight Loki's forces of evil and cause billions of dollars worth of damage to Manhattan. What Whedon did rather well was devote equal screen time to the main Avengers (the ones who already were major players in their own films). However, the lesser Avengers were left on the wayside as both Black Widow (Scarlett Johansson) and Hawkeye (Jeremy Renner) were left underdeveloped, but the latter to a greater extent. It's different here in Avengers: Ages of Ultron as both Black Widow and Hawkeye are developed further, particularly Hawkeye.
Black Widow is developed by her relationship with Bruce Banner (Mark Ruffalo) but it's Hawkeye who gets much of the attention. In the first Avengers Jeremy Renner had very little to do, this time Renner has more quips to make, more wisecracks to crack and more villains to kill. It's refreshing that the most human of The Avengers is the one that's mostly humanised in the recent Avengers film. Credit also goes to Renner who has good comic timing and does a good job at bringing out the wit in Joss Whedon's script.
The Avengers and its sequel is best when The Avengers are interacting with one another by making jokes, gently teasing each other and arguing amongst their selves. There is slightly less of this in the sequel as the film takes a more darker outlook than it did in the previous film. This may be the reason why the sequel isn't quite as enjoyable as the 2012 Avengers film, but despite this when the characters are interacting with each other the film its very much within its element and praise for this must go to Whedon's witty screen play that does a good job at fleshing out its characters even though there are arguably too many.
One of the problems with the sequel is the action sequences, there is nothing drastically wrong with them, they are well staged and elaborate as they should be in a superhero movies. However, sometimes they are so overly chaotic that it's difficult to keep track and with their rather long length it does become rather tiresome trying to keep up. Things do clear up in a exciting and tense finale because you do generally feel that the characters are at risk. The major action sequences aren't too different from the first film but instead of an American city getting a battering it is Seoul (probably why the film's a hit in Korea) and some made up city in a made up country doubling as Slovakia (probably) that has a large bill to pay.
The villain hardly strikes terror among the audience amongst despite his legendary prowess (as a villain he isn't nearly as much fun as Loki), however there are some interesting new characters (Elizabeth Olsen's Scarlett Witch has some creepy moments) but Avengers: Age of Ultron isn't much of an improvement over the sequel neither is it really any lesser of a film. Pretty much same old, same old.