Messages: the Inbox has a new look, the same as the WhatsApp conversations screen. Your conversations are listed on the left with photo, subject and the latest message, and unread ones are marked. The open conversation shows on the right as chat bubbles, with older messages loading as you scroll up and new replies arriving by themselves. Type your answer at the bottom and press Enter to send, or attach files with the paperclip. Ticks show whether the other person has read what you sent.
Messages: switch between Inbox and Sent items without reloading the page, and search your conversations by name, subject or text. A message written with the new-message button opens straight away. On a phone, the list and the conversation take the whole screen, one at a time.