Clash between “two good guys” was already tried in Avengers 2, between Iron Man and Hulk. And someone decided it’s an opportunity to make an entire movie out of it. Just without Hulk.
Main conflict can be described as “Lawful Good vs Chaotic Good”. Irony being that a rather chaotic Iron Man is on the side of Lawful.
One of the main problems is that since it’s a Captain America movie, there’s a lot of Winter Soldier in it. I don’t like how Sebastian Stan plays, and his superhero is boring as well. The only interesting part about him is this piece of hardware he totes as some point:
The “threat of the week” is revealed an hour into the movie. And honestly, it doesn’t even sound that threatening. What’s a few Russian assassins after you dealer with a full scale alien invasion and an army of robots?
Twist with them being offed in their sleep is actually good, though.
Idea of a “regular guy” trying to get revenge on superheroes for inadvertently killing his family is alright. At least it’s not yet another Ultron this time.