Hide the Document Outline: You can now toggle the document outline on and off through a setting in the View menu. Whichever setting you choose will apply only to you and will be remembered for the document.
Set a Custom Date and Time Format: Spreadsheet cells can now have custom date/time formatting. You’ll find the option in the Spreadsheets toolbar under the More Formats button (that’s the one that says “123”). A list of common formats (including the ISO 8601 standard!) are available to quickly apply—or you can pick and choose the format that works best for you and your team.