While nice in theory, it's annoying in implementation so I've turned it off. If you want to check a new mail and it's in a thread, clicking on it takes you to the thread and it's one more step to open the new message. Likewise, once you've finished reading a message, it takes you back to the same thread that you've already read and it's one more step back to inbox.
Hopefully they'll enhance it so it behaves like Gmail where opening a thread takes you to the unread message and exiting it takes you back to inbox.
Hopefully they'll enhance it so it behaves like Gmail where opening a thread takes you to the unread message and exiting it takes you back to inbox.