Mini-Review from an adults perspective: Strictly speaking the movie is the weakest of the recent Marvel movies, and not nearly as good as Iron Man 1. For what it is, it's well done, but it suffers from one too many plot lines, which bogs down the pacing and ends up being drawn out too long. My son felt the same way actually, without me even projecting my opinion about it.
Parental Review: Both Iron Man movies tell a story part cartoon, part parable of a self-centered playboy who learns to care about the world rather than see it as his big playground. The violence in the first is much more realistic and potentially scary, though our son was OK with it. A lot of it is context, and what is implied is much more scary from an adult's perspective (knowing what the world is really like and what is happening off-screen). But I have found what my son doesn't see he generally doesn't have the context to fill it in, which makes the impact less violent or scary for him. It might actually be more intense for a 10-12 year old than a 6 year old in some ways.
Anyway, both Iron Man movies have been great for conversation with our very mature six year old. Frequent pauses in the first halves of both movies helped explain the bad behavior being displayed and how Tony Stark might learn from it later, but that's a good thing IMO. It's more interesting for all of us to explore what it means to be self-centered but learn and grow from that then having an obvious or one-dimensional hero. Sexual inuendo goes right over his head so we leave that for a later age. When Tony brings home the reporter in the beginning of the first movie we just left it at "It was a sleepover" and that worked for him. All the recent Marvel movies have had heroes that are fallible or conflicted in some way, and it makes for good converstions during or after. Though Capt. America has the most true-blue hero (no pun intended) it still has plenty to explore with the character's motivations and bravery well before he's a super hero.
One more language detail for Iron Man 2: though it's said with a heavy Russian accent, at one point Vanko declares to Justin Hammer: "This software is sh**." It comes out as "Thees softwaya ees sheet." but it's worth knowing before hand. Apparently even the official Common Sense reviewers didn't notice so maybe most others don't either. As we don't ever swear around our son, I've found the infrequent but notable swearing in the Marvel movies seem to completely get ignored by him. I assume if he doesn't know what the word is he just takes the tone of the sentence for what it is, and doesn't bother even asking what he just heard.