First reaction upon removing an ESP-12 from the anti-static bag: "Hey! These are surface-mount. I guess I get to figure out how to solder surface-mount components a couple weeks ahead of schedule." My soldering irons may not be up to the task, but could one not reflow solder these in a toaster oven? I've got the solder paste and could experiment on some veroboard first. Sound crazy? I'm not sure if the header pins would survive the toaster oven treatment and may choose to solder them with a soldering iron instead.
Second reaction: "Hey! The adapter board doesn't break out the pins on one end of the ESP-12 module." A couple more GPIO pins won't make or break me, but it looks like hardware SPI is on those unconnected pins.
The quality of the ESP-12 boards looks better than the ESP-01 boards I received. At least, the stencilling is much more legible.