To view your slides in Grid View, click on "View" across the top and choose "Grid view" from the list. You can also look at the bottom left corner of your Slides window and see the little icons to swap from standard view to grid view.
There are a few more features they just added, like Add-ons and Google Keep integration, that you can read about in this post from Google.
If you don't see the "Grid view" option in your "View" menu - don't worry. It is still in the process of rolling out to all domains. Hang tight and you should see it soon!