Thanks to more collateral damage while the Avengers are out doing their thing, the world has decided to reign in all these enhanced individuals to make them work for the UN. This divides the team on the accountability vs freedom front and one very lucky bad guy manages to leverage this into a more violent and entertaining conflict where heroes fight each other.
We're not fighting, I'm just repairing Cap's shield.
What's good? Marvel characters galore with quality acting, humorous segments that made me laugh along, nice action choreography and high budget CGI. Introducing even more characters in an already large line up seemed like a bad idea to me but they pulled it off just fine. I also quite like the idea they had behind the bad guy, who really is nothing special - a good contrast to all the powered folk of the Avengers.
On the negative side the biggest issue for me is that said bad guy was extremely lucky that so many things went his way for as long as they did. There's one bit where he would have had to get past a number of security check points AND somehow kill backup generators in what I'm guessing is a high level building, unless of course there are no backup generators in a world where they have underwater prisons and guys that fly in suits of armor?
It's not explained how he manages to do all of this, he just does, which is a bit annoying. The other problem will be for anyone who hasn't watched the Avengers or the previous Marvel films - you could get lost really quickly with "who is that again" even with the 3 minute intros. All up I enjoyed the film and give it 4 Vision lasers out of 5, even if it is a "moving pawns across the board for the next movie" sort of thing.