It is not fair to compare Docker with Debian. Docker Inc (who backed Docker) is a for-profit corporation and is backed by investors. It is understandable why they need to push their products into production the soonest time possible.
"Production ready" in the "container space" for me are Solaris Zones, FreeBSD Jails, and to an extent lxc (it's stable, but I've used it less). I like what Docker/Mesos/etc. bring to the table, but when working with the ecosystem, it takes work to stay on top of what is going on.
It is even harder to consult with a customer or company interested in containers and give the most accurate near/long term option. It becomes a discussion in understanding their application, what approach works now, and guidance for what they should consider down the road.
Networking and Storage are two areas with a lot of churn currently.