I bought two last year for wedding photography. I dont use it for video so can't really comment on it's abilities in that area.
Autofocus: It's not a 5D3, but I think it's better then the 5D2 and most people considered that to be an awesome wedding and event camera. The autofocus points are tightly clustered in the center so focus and recompose is required, actually just ignore everything other then the center focus point. That one focus point is jaw dropping, it can see in the dark. I used it during the first dance and was getting at least 80% of the shots in focus. (very happy)
Image quality: Good, but then all full frame cameras from either of the big two are good. What I really like as a wedding photographer is that the usable ISO range is 100-6400, above that it gets a bit ropey. This is the sort of camera you can use for dark church ceremonies where you aren't allowed to use flash. More then enough MP for anyone, can easily do A1 prints. (very happy)
Card slots: A single SD card, it works fine for me. Would I prefer two slots, yes but it's not a deal breaker. The lack of CF is not an issue, SD cards are fine. (happy)
Construction: Lightweight but solid. It's not a tank, I doubt it would like being dropped onto concrete but its as good as any of the prosumer bodies. They had to make the top plastic to let the WiFi and GPS work. (happy)
Wifi & GPS: A fun gimmick, the wifi camera control sounds useful but I find the lag is pretty horrific. I have used it during the ceromony hidden near the couple to get shots without getting in the way. The GPS murders your battery and is useless for me (others may find it essential).
Colour/exposure: Nails exposure fairly well, colours are nice and vibrant once you set up a lightroom preset. Gives nice warm skin tones by default. (very happy)
Battery life: A single battery lasts for a full day wedding shoot, unless you leave GPS on. (very happy)
Overall: Not bad for the price at all. Get the 5D3 if you shoot action due to the better AF and larger buffer. For weddings, events and portraits I recommend the 6D. I got the battery grip for both of mine as it was a free offer, but I don't think it would be worth buying them otherwise.
Too subtle perhaps? The 6d is most of the 5d3 for a grand less money. I struggle a bit to see why the majority of photographers would need the 5d3, but nobody talks much about the full on pro camera the 1dx. I'll bow out of any further discussions on the matter as its boring now and going off point.
Bought mine with 24-105 as my bad back was struggling to cope with my 1D's. Nice camera, nothing like as quick to use as 1D, autofocus in particular is slower. Happy with mine, it fulfils the function it was bought for but will reserve final conclusion until I have used it with other lenses, as yet I have have only used it with the 24-105. Using it at higher ISO's is far superior to 1D mk3, really clean images at ridiculously high ISO's.