Four new features enable the technology that runs your inbox to truly work for you:
Nudging: A brightly-colored box will appear when you've ignored an email for far too long, letting you know that it's time to finally take the plunge and do so. And while that may seem like an instant heartburn generator, we promise your friends, family, and coworkers will be grateful for this one.
Smart Reply: Based on the emails you've exchanged in the past, Gmail will now populate and offer a simple response to each and every email. It's only available on mobile right now, but here's what makes it truly useful: if you're one of those people who hates exclamation points, it'll know, and won't give you those annoying-as-hell suggestions that you'd never in a million users deign to use.
High-priority notifications: This is another feature that's only going to be available on mobile for the near-ish future (sorry, desktop Gmailers!), but it's one of those things we've all been waiting for, and hopefully it'll have been worth the wait. Basically, based on the emails you open, read, and respond to, Gmail will only show you push alerts for the emails that are really urgent, and let you check out the ones that aren't when you open your inbox.
Unsubscribe: I've been using the half-formed version of this feature for a while, and it's a lifesaver. Now, it's easier than ever to unsubscribe from those emails you get a little bit too often, and Gmail will even point out the most pesky ones to you along the way.