I have so many thoughts about Age of Ultron, so I will try to give them in the least spoliery way:
The movie itself is not as dark as I thought it would be. Yes people die, but not in uber graphic slamming car doors on heads (Netflix Daredevil reference) way.
Ultron is a pretty bad dude, James Spader does an amazing job showing that, but he is not as physically terrifying as the Chitauri from the first Avengers movie. Ultron is more terrifying on a mental level and leaves you thinking about the future of humanity.Your kids might not have nightmares about Ultron.
Black Widow and Scarlett Witch are amazing!! ScarJo and Elizabeth Olsen prove that women heroes are just as strong as the guys and that they can hold their own against Ultron and his robotic minions. I left the theater wanting to see either solo movies for both characters, or a Black Widow/Scarlett Witch team up movie.
The Vision was not what I expected, and I loved it!! Some people might not like this portrayal of The Vision, but I am not one of those. The Vision fits perfectly in the MCU and I was sad that we didn’t get more.
The movies touches on the idea of men playing God and the consequences of those actions. The undertones might be a little too advanced for the little ones, but if they love the action of Marvel movies, they will love Age of Ultron. My recommendation is too watch the movie with your partner first, and then decide for yourself if it would be good for your child. I personally loved the movie and think that you will not be disappointed if you are a fan of the MCU. .