Mild spoilers inside the cut tag, but probably nothing that you couldn't glean from the trailers...
The first thing that you have to understand is that this was the named plot line that turned me off of Marvel Comics so that I now only buy a small fraction of their output, mostly based on the writer. I was predisposed not to care that much for this film and, as it turned out, I didn't.
Part of the problem is that I am tired of the no-win scenario and this was doomed to be one of those. Lots of fights, lots of explosions, not a lot of favorable resolution.
The good things about the movie can be boiled down to two: Spider-Man and Ant Man. Three, if you count Black Panther, and I really only liked the character when Christopher Priest was writing him. I did recognize some elements that he added to the character, so that's a plus. But the first two were the only parts of the movie that weren't grim, grimmer, and grimmest.
In any case, this was more Avengers 3 than Captain America 3. The action was pretty much driven by the previous Avengers film which shouldn't, I suppose, be a surprise.
But there just wasn't enough that I liked about the film.
And that's a shame.