Phil has a point there, it's a bit like when some of the higher spec Canon 35mm film SLRs had 'eye controlled focus'; it didn't work for some people (possibly as they were wearing contact lenses, glasses or couldn't get to grips with calibrating it correctly for their eye) so they moaned about it. I found it worked very well, as I think did a lot of people who used it, and my reply to those who complained about it was "Don't use it then, it's not compulsory, there's an off switch!".
I think I've used the video feature on my 6D twice since I bought it nearly 4 years ago, and it did a good enough job, but I have a camcorder if I want to shoot HD video. It's handy to have the video feature all the same, but I tend to forget it's there. For me it's a bit like one of those tools on an up-market Swiss Army Knife, it's useful to have if I ever need it, and it shows I didn't buy the poverty model!
I know some folks seem to like using DSLRs for video, but I've never really understood why they just don't use a decent camcorder instead?