Switched to 5.0 beta last night. Looks good.
One thing I've noticed...if I use any of the new themes, my message list in the mailbox view doesn't display properly. In any of the old themes (sand, steel, etc), it still works fine, but with a new theme (waves, gorilla, etc), the list elements in the message listing will only display one message at a time, no matter how much I expand that listing area. See attached screenshot.
Any idea how to resolve this?