I'm actually a terrible judge on these sort of things. I have to admit that I am somewhat desensitized to a certain level of violence in movies.

As far as sexual content goes, definitely less than Iron Man (I don't really remember there being any in Iron Man 2, but I'm sure that there was). Tony tells a couple of crude jokes. In a flashback scene, there is an implied one-night stand (though absolutely nothing is seen). Tony and Pepper lie in bed together (unmarried, it is assumed), but they don't do anything sexual. Several women (including Pepper) get some screen time in their underwear, but it is less than in X-Men: First Class. There is a really weird large stuffed bunny with big breasts (you can actually see this very briefly in one of the trailers at 1:19. No, I'm not the one who noticed it. A colleague messaged me Thursday morning after watching the trailer to ask me if he saw what he thought he saw, so I checked it out. From the trailer I couldn't really tell what it was, though it was obviously something inanimate with large breasts. There is no question about what it is in the actual movie, though.)

As far as violence goes, there is definitely more than in the previous Marvel Cinematic Universe movies. It is quite a bit darker in tone, too (though there is still quite a bit of Tony Stark's humor). Is it too violent for younger children? I'm really not sure. I think that if they've seen the others it is probably alright on a home TV. The violence is more pronounced in a movie theater, though. I think that if I had let my own kid see the others, I would probably let them see it in the theater, but without actually being a parent, it is hard to say for sure. If there is any way to do so, it might not be a bad idea to watch it first and then decide.