Three things I find annoying...

(1) Chat Type lag... takes forever for the things I've typed to follow on the box as I type them, its like the client can't keep up to basic typing speed.

(2) No autofocus on the text box... I go to send a message to a buddy, start typing away and get nothing becuase the cursor doesn't automatically begin in the text box. I need to open the buddy window, click the text box and then start typing.

(3) The scroll bar doesn't always follow the chat. When it fills the screen the chat sometimes just scrolls off the page without the scroll bar keeping up with it.