The two things that the 6D is lacking that I think are important to a amateur/prosumer photographer are a second memory card slot and a pop-up flash. I just purchased a Nikon D600 for my father, rather than the 6D, because the D600 had the second memory card slot and a pop-up flash.
I could care less about WiFi and GPS....and video for that matter! I think Canon should have designed this camera geared toward purely still photography, and left out the video, which would have kept down the retail price and Canon might have been able to price it around $1,500. The Nikon D700 doesn't have video, and look at how many still love that camera!
I am fascinated as to why people feel a second card slot is worth a dime, I have had one for years and rarely use it, even then it is only for an Eye-Fi, something I could easily live without. Why do people value a second card slot so highly?
dual slots can be used as a raid setup so writing the same to both cards , that way you don't have to pull all your hair out of your head when a card goes corrupt
or shoot jpg on one and raw on the other so on events you can ofload the jpg's quickly and keep the raws as backup