• All your inboxes in one place―view all your mail at once, regardless of whether it’s from your work or personal accounts, using the new “All Inboxes” option. This way you can read and respond to all your messages without having to hop between accounts.

• Conversation View―if you’ve set up separate inboxes in Gmail for your Yahoo, Outlook.com and other IMAP/POP accounts, messages in these accounts will appear neatly stacked as one conversation, just like your Gmail messages.
• Smarter Search―searching in the Gmail app for Android now comes with better auto-complete, so you can find what you need even faster.
• Other helpful features―larger attachment previews to help you see what’s inside, the ability to save to Drive with a single tap, and new animations that make opening and closing conversations more smooth.

Source: Google Apps update alerts