Rich Text Formatting
Now you can add bold, italic, underlined, colored and highlighted text to your email—all from inside the mobile app. These new options are great for making a point or emphasizing what’s important.
Instant RSVPs
If you use Google Calendar or Microsoft Exchange, calendar invitations now include a one-tap option to show your schedule and respond. No more opening up separate apps just to see if you can squeeze in a meeting.
Source: Official Gmail Blog: Productivity at your fingertips with rich text formatting and instant RSVPs