seems interesting but please enumerate things I can do that are not delivered by docker compose and docker swarm.
For example, Flynn comes with PostgreSQL, MariaDB and MongoDB appliances which are deployed in a highly available, fault tolerant configuration with sane defaults: https://flynn.io/docs/databases.
Through the use of buildpacks, it is also straight forward to deploy applications written in many popular languages and frameworks without being intimately acquainted with how to containerise those types of applications (e.g deploying a Ruby on Rails app on JRuby: https://flynn.io/docs/languages/ruby).
You also get things like full cluster backups (including all your data), simple git / docker / tarball based deployments, log aggregation, release rollbacks, domain / path based routing, service discovery, and many more!
The Docker-PaaS movement reminds me of content-management systems in the early 2000s. Everyone (myself included) thought it'd be great to spend loads of engineering effort reinventing the wheel, instead of delivering business value.