I used the redesign before it became standard for everyone. I opted-in for the Beta and I enjoyed it (and thus never changed back). I found it made everything a lot easier to use and a lot cleaner. But a lot of people didn't.
What's weird with human nature is that humans aren't fans of change. When a change happens around the web our human instinct is to react with upset and fear and anger. YouTube is our home for online video, and so when that home changes we of course feel angry about it. But here's the interesting thing, we start using it and we get used to it.
When the Beta came out for the new design, you could op-in and then you went to a video page of a documentary called HOME. Of course, when I read through the comments I found an overwhelming abundance of people yelling out "THIS LAYOUT SUCKS!!!!!!". But now people are fine with it. They get used to it. And then they change another thing and people freak out.
It happens all over the 'net. On Facebook, Twitter and any other social media site.
Whilst it is human nature to be angry and afraid of any change that comes at us, it's also human nature to adapt and change with it.