i use flash(es) ALL THE EFFING TIME, so believe, i understand the limitations of 1/180. however, this camera is not aimed towards people like that. this is basically a rebel/x0D series camera just FF.
I only know a single Rebel owner that has an external flash -- everyone else uses the on-camera flash. That's the thing I don't get about the 6D. A lot of people are talking about how this is aimed at the casual / "soccer mom" photographer. However, why would Canon leave off the on-camera flash in such a case? In addition, if one must use an external flash, why limit it to 1/180s sync speed? In addition, why not add an articulating screen, seen by many (incorrectly, IMO) to be a consumer-line feature?
I also don't see this as the FF upgrade path for 7D owners. One of the primary highlights of the 7D, at the time it was released, was it's very sophisticated AF system. Heck, that's still one of the primary selling points over the other crop cameras. Are many 7D owners who bought it for the awesome AF system really going to go for the 6D, with it's 11 AF points + 1 cross-type? Yes, the AF will work in very low light levels, but it's still an extremely limited AF system for anyone coming from a 7D. Motion tracking with 11 pt AF? Oy.
Maybe it's for landscape photographers who don't use the flash much and who aren't worry much about fancy AF systems. I suspect the high ISO noise performance will be good, though I cannot imagine, for the life of me, that it'd be any better than that from the 1DX or 5D MKIII. After all, Canon wouldn't release a $2100 6D with better noise performance than the recently-released, $3500 (list) 5D MKIII. In addition, I can't imagine that Canon has "fixed" the shadow banding problem common to Canon sensors (see Fred Miranda's nice 5d MKIII vs. D800 comparison for this), otherwise they would have implemented it in the 5D MKIII.
Is the difference between the sensor in the 60D and the sensor in the 6D really $1100? The AF in the 60D is better, and the 60D has an articulating screen. Really, it looks like only real benefits of the 6D over the 60D are the dual-SD slots, the FF sensor, and the built-in WiFi and GPS. I know Canon sells add-on GPS units for ridiculous amounts of money, but GPS units are extremely cheap now-a-days, so it's not like adding GPS to a camera really costs Canon much money.