My understanding is that the per pixel noise performance is about the same as the 5D II. (Source: DPR.) Note, that's per pixel noise, so per image noise is of course significantly lower.
I've been saying for years now that Canon has become so obsessed with video that they have forgotten about photographers. These two, together with the 7D II, suggest that they have been listening. Good work Canon!
Will I get one? Possible, but probably I'll look at a 5D IV. Tempting just the same.