In the new interface, the query or mailing template ID has been removed from the URL. This makes it particularly difficult to share work with colleagues for checking easily. Before you could send them the URL and now you need to send them the path to follow.

This is also affecting viewing contact records - when you view the contact insight for a record, you used to be able to click on the emails they had been sent, and it would bring up a copy of the email they received. Now click it takes you to the generic login page which isn't useful for verifying what emails people have been sent.