Unlike the last film of the 'Avengers Assemble' series 'Avengers Age of Ultron' Ant-Man was actually fun. There wasn't one point in the film I can think of that was a 'that's dumb' moment, maybe a 'meh' but nothing to take me out of the film like the 'sun's getting real low' or Ultron. But this film finally did what the Marvel films of old had not had the guts to do, they killed a character. Now Ultron killed Quicksilver, but just like in Ant-Man it was not that much of an important character. To me Antony was better written than the 'Marvel' Quicksilver. Also the villain 'Yellow Jacket' is murdered by Scott, in every other film, the bad guy just went to jail. (Ultron was a computer, there for I don't count as life)
Even with the final scenes they've got back to the old formula of both scenes bringing something to the film, unlike the last few Marvel Films. Now Guardians had one scene which extended the story, but the last scene with Howard the Duck was just a gag like the overrated and stupid shawarma scene from Avengers 1. Avengers Age of Ultron had Thanos grabbing the gauntlet and no ending scene. Because Whedon couldn't 'top the shawarma scene'.
In Ant-Man the two scenes foreshadowed the Wasp becoming a superhero in her own and revealed Cap and Falcon finding Bucky and saying that they were on their own. Showing that the war between Cap and Steve had already begun.
I give Ant-Man a B and putting it at number 4 on my list of Avengers films,
1) Captain America : the Winter Soldier
2) Guardians of the Galaxy
5) The Incredible Hulk
7) Avengers : Age of Ultron
8) Captain America
10) Thor : the Dark World
11) Iron Man 2
12) Iron Man 3