I like the newest version of Outlook, but it has few annoying features that I do like. One of them is when you reply to a message, Outlook defaults to composing the reply in the same windows the showed a preview of the email… I prefer for a speparate window to pop out that allows me to compose the reply. I have also customized the toolbar which does not appear in the main Outlook windows when composing the reply.
Here is how to configure Outlook 2013 to default to composing reply messages in a different window: