The situation's gotten much better since Armbian started building images[1], but it's still running a stranded kernel for now. This is expected[2] to change within the next few months. I've heard on IRC of people successfully running mainline Linux on the A64 SOC, but I don't believe it's recommended.
As far as China single-board computers go, I'm pretty pleased with Pine's build quality and attention to detail with regards to electrical design that's reflected in their schematics. Community-provided Linux support has come a long way in the last year+, it's worth checking out.
[1] http://linux-sunxi.org/Linux_mainlining_effort [2] https://www.armbian.com/pine64