I think the new design: https://twitter.com/twitter is pretty ugly and puts the author's bio and URL in an odd place. The banner image will interfere with that text and make it difficult to read.
I'm curious why they didn't roll out this layout to everyone: https://twitter.com/yankees It's much cleaner.
I could previously see 6/7 of the account's previous tweets (on a more-standard resolution than most devs are used to),, now I see 3. All for a blue-ish box.