1. The Action Scenes
If you thought the fight scenes in the first Avengers were good then the fight scenes in this will blow you away. From Iron Man's battle with the Hulk to The Avengers taking on an army of robots the fight scenes are action packed and fluid, with brilliant choreography.
2. The Character Development
We don't only see the Avengers grow as a team, but as people in this installment. We see Tony struggle with his fears, Natasha battle with her desires, and Bruce question his place not only on the team but in the world. Also we learn more about the personal lives of two Avengers in particular that will surprise some movie goers.
3. New Characters
We meet some new characters in this installment. The Maximoff twins, Ultron, and Vision all make their debut appearance. Ultron as a villain is very interesting as he truly believes he's doing the right thing. The twins were my favorite part of the film, being a fan of Quicksilver and Scarlet Witch, and fellow fans won't be disappointed. And Vision...well you have to see the movie to understand how amazing he was. All these characters, especially Vision, mark a change in the Avengers and will no doubt have lasting affects in future films.
4. Set Up for Future Films
Avengers: Age of Ultron sets up a lot of stories for future films, particularly stories involving the infinity gauntlet. I won't spoil it for anyone, but there is a scene after the credits you should stay after for. With all these elements brought up in Age of Ultron Marvel continues on in its ever expanding web that connects film to film.
5. It's Just Plain Fun
Avengers: Age of Ultron at its core is just a fun action packed superhero movie. Yes there are some serious and heart felt moments, but the movie keeps a light hearted and humorous tone through out. This is an element that some superhero movies neglect, wanting to go for an all serious tone, and fail to realize you can tell a serious story about life and death, good and evil while also making your audience laugh from time to time. In Age of Ultron you will laugh, A LOT, and that helps keep the movie enjoyable.
All in all Avengers: Age of Ultron is not just an awesome superhero movie, it's an awesome movie period. Assemble and go see it!