For me, this was more of a "Oh, I know what that is!" *giggles maniacally at the thought of Cosmere-clueless people reading this book*
Really, the Cosmere was the biggest shocker of all. I thought that I noticed similarities between his worlds, like the physical, spiritual, and cognitive realms, but discounted them as attributes of Brandon's techniques for world-building. I had read everything by him at the time I found the Cosmere, so it was a lot of sparks going off.