Not yet. Not a detailed one, anyway. The few play test games mentioned on the Stalker7 site are deliberately vague on the specifics.
It's modern era Nightwatch with a bit more crunch. If you're familiar with Hardwired, NW TnT, and Insurgent Earth, you know the basics.
Nightmares adds traits to flavor enemies, makes space for little storytelling cut scenes prior to combat, and introduces a little more grit to the hunter/investigator characters and their abilities. It's civilian vigilantes against monsters in a world where everyone is skeptical of both.
I'll post battle reports after the game's UK release.
I have to say I sense a lot of people have a lot of expectations for WNC. I do hope most of them are pleased with it.