A possibly bad thing I see about this, there seems to be a segmentation of sorts. I've noticed there are now a few conflicting editions of Docker Engine. There's CE and EE now, then there's some version that Docker Cloud Agent bundles, and probably more. (Maybe I'm wrong, though)
Maybe that's just me, but it would be better if there'd be one core to rule them all, and extras would be managed by plugins/wrappers/companion daemons. So if you have Docker Engine installed you're good to go.
One of the goals of this release is to remove this fragmentation. For example Docker Cloud will use CE, and soon will allow you to easily upgrade to EE.
In the free / open-source side, Docker CE is the "one core to rule them all" that you describe.
I just didn't wanted to have different daemons (server, not client), and having to replace them if I'll want to use Cloud, EE or whatever (or stop using that or replace them with something else, etc).
Docker CE and EE are based on the Docker open source project and work the same way. You can also use a Docker CE client to talk to Docker EE host or swarm, and vice-versa.
The Docker Cloud team is working on improvements to reduce segmentation too - stay tuned.
Maybe that's just me, but it would be better if there'd be one core to rule them all, and extras would be managed by plugins/wrappers/companion daemons. So if you have Docker Engine installed you're good to go.