I was so used to the old YouTube design that it never occurred to me how ugly and impractical it actually was. Gladly, the Google guys (YouTube is part of Google now, just in case that’s news to you) currently redesign all their services to fit in with Google+.
On YouTube, you have to enable the new design called Cosmic Panda yourself. Go to this page and hit the big button to do so. I strongly recommend it , even if you’re watching YouTube videos just occasionally.

Thx to Jeriko for mentioning Cosmic Panda on Google+.
GigaOM gathered some comments on Cosmic Panda from YouTube content creators.