The new wp_list_comments means that the size of avatars can no longer readily be set manually, but I don't see anywhere in the admin panels to set the size. Presumably this should be added under Settings > Discussion, with the other avatar settings.
The other quirk I'm running into looks like a layout issue: on short pages the Settings menu item is hidden underneath the admin pages footer and I can't click on it. Yay for absolute positioning; perhaps a z-index statement is in order?
Similarly, if any content in the main area overflows the right side, no scroll bar appears and there's no way to get to that, either. So far this has happened with the auto-upgrade messages and one plugin. Overflow:auto, please?