I don't think the Primer is likely to get deep into explaining the system, but who knows, maybe I'm way off on that.  People already familiar with FATE or PDQ can probably make general sense of the previews that have been posted - I think I get the gist of it, in any case.  People who don't might want to poke around the evilhat wiki...

The Primer sounds like something we probably all already have in our heads, being Dresden Files readers; I'd say 'Things that go Bump'.