To us it appeared yet another in a sea of many orchestration tools that will give you a very quick and impressive "Hello World", but then fail to adapt to real world situations.
This is what Kubernetes really has going for it, every release adds more blocks and tools that are useful and composable targeting real world use (and allow many of us crazies to deal with the oddball and quirky behavior our fleet of applications may have), not just a single path of how applications would ideally work.
This generally has been a trend with Docker's tooling outside of Docker itself unfortunately. Similarly docker-compose is great for our development boxes, but nowhere near useful for production. And it doesn't help Docker's enterprise offerings still steer you towards using docker-compose and the likes.
"BUILD SHIP & RUN, ANY APP, ANYWHERE" is the slogan they repeat everywhere, including here, and it means even less everytime they do it. What IS Docker Cloud? Is it like Swarm? Does it use Swarm? What kinds of customers is Docker Cloud especially good at helping? All these mysteries and more, resolved never.
Heroku should be an interesting learning example to the tons of new age cloud PAAS that I'm seeing. Heroku database hosting has always been key to adoption.. to an extent that lots of people continue to use it even after they move their servers to bare metal. The consideration and price sensitivity to data is very different than app servers.