Does Ant-Man Work as the Final Chapter of Phase 2?

Yep.

 

I think it does. After the biggest Marvel movie so far, they tone it down and introduce several new characters, and add to the history of the MCU. It also serves as a nice bridge from Age of Ultron to Civil War.

Phase 3 should definitely start with Civil War.

 

Felt like the perfect end to Phase 2. Civil War will be the perfect film to start Phase 3.

 

To be honest, since there's no real time gap or differences in style between phases, you could pretty much just call it the start of phase 3 anyway.

That being said, it's a nice way to bring the overarching tension of the story down. With everything getting cosmic and magical and whatnot, Ant Man does its part to bring it back down to Earth, and keep it simple. It's refreshing, and as opposed to how a lot of these movies get weaker when they try to introduce the larger MCU, Ant Man benefited from it. It didn't feel as much like it was trying to sell a movie to you, like how Captain America 1 tried to sell the Avengers.

It's nice to have something small between all the big happenings of the MCU