The Cosmic Panda update will not affect your Youtube channel ranking or views in any way. It's mostly a visual upgrade that changes how Youtube pages look.
You get more options for how to design your page, which is totally awesome. Everyone can upload a custom icon, and you can feature playlists on your page much cooler than before.
For Google Chrome users Youtube supposedly works faster. With the Cosmic Panda update you can continue watching a video while browsing around on Youtube.
Check out the official Youtube Cosmic Panda Page, you'll need to go to 'Test Tube' if you want to try out Cosmic Panda which is currently in beta.