If you've been following our blog, we introduced a new addressing widget where contacts appear as bubbles that appear inline, and are easy to manipulate. However, we didn't stop there. You'll find that we redesigned the Compose Window with a much cleaner interface.
The most notable change other than the contact bubbles is the location of the From field, now tucked neatly underneath the toolbar. It's slender, but still easy to access. Also, if you're missing the button to add a CC or BCC field, you can find them in the View menu, or you can use a keyboard shortcut to toggle them (Option + Command + C, Option + Command + B on Mac).