With respect the the Samsung:
Autofocus: good in bright light, passable in low light, it really is better than the old canons (5Dii) in mid-low light. Nowhere near the newest AF SLRs. There is no good way to control focus in C-AF mode.
Weight: Very nice! Even with the 16-50 f2-2.8.
Durability: Appears to be at or above the 5Diii level. Not quite as overbuilt as an D810. It feels basically like a 7D.
Usability: Complete garbage! Nice button placement but boneheaded firmware. In video mode, we let it slide because the video is so awesome.
Support: 2 Firmware updates already, new ones on the way (sadly these ones are video focused).
Weather Sealing: S lenses are gasketed, body appears robust. We won't know till someone tears one down though.
Lenses: 24-70 eq available and quite good. 70-230 eq reportedly of similar quality sharp and fast. Neither are landscape lenses. 85mm f1.4 (135mm eq) check, very sharp very corrected a bit high on CA but its a system of lenses that are supposed to be software corrected. 60mm macro check. 30mm pancake check. UWA zoom check minus.
Viewfinder Quality: A new standard as far as latency, good sharpness as compared to A7.
Lightroom support out of the box: It includes a copy of lightroom! Sadly no Capture One support other than through an included DNG converter.
At the moment it really is an astounding 4k video camera.
Stills are good enough for events, there are reports of sports working fine if you can fill the frame. Its a PITA for slow fine arts stuff because of wide open focusing and a nerfed AF-S mode.