[DDAM]aipheeAgree that Battle Chat as a regular chat channel... especially one that *doesn't close when you leave the battle* is bad behavior.
There are lots of large and small opportunities for improvement - the home screens are terribly over-cluttered, the skin on both the lobby-UI and the website is generally ugly, and could use a good designer's touch.
Licho deserves a lot of great credit for implementing a lot of fantastic functionality, but iirc he's freely admitted he's waiting for somebody with design talent to fix up buttons and the like.
Many of the panels in the various listings are cluttered, and the Web vs. Winforms pages could use some unifying theming (why is Chat and Battle listing white while the website is black)?
I'd also love to see messages come through as some kind of GChat-style pop-up instead of appearing as new chat-channels.
My fantasy approach is a right-sidebar panel for direct chat messages, votes, and other message-like content.