Now Inbox search works a lot like Google Search. Google autocompletes your query and shows results as you type. There's also a "top results" section that shows the most relevant 5 results for your query. It's not perfect and it's easy to see why this doesn't replace the standard "sort by date": ranking email conversations is harder than ranking web pages. There are no links between messages, many messages are pretty short and are only important for a short while.
In addition to top results, Inbox also shows quick answers extracted from your messages. "Now when you're searching for a frequent flyer number or shipping status, Inbox will show it at the top of search results – no more digging through individual emails to find what you're looking for."
Quick answers are very big in the desktop site: