It's actually a really good advancement as Google begins to dominate the entire technological world, and not just the pc/web, but mobiles and tablets (android) and now they've got the Google TV. That's what this is preparing for, youtube moving on to TV as TV's becoming more connected to the internet. Don't believe me? Google even explains that the profile art dimensions are made so that they suit a TV screen.
Just looking at it on the web though, I think it offers a more level playing ground for all youtubers, especially those that can't afford or are unskilled in graphic design, since the focus of the community is on actual videos after all. Some channels are just an eyesore too. I think this looks more professional. I would like to be able to have a light theme and a dark theme across the whole of youtube tho.