Joanna Stern, personal technology columnist for The Wall Street Journal has it right... "The killer feature: Search."
But then, we sort of knew this, right? It's Google's Internet... when it comes to indexing information they're the King. Take this concept and apply to your photos. Each picture is basically layers upon layers of data. Hand over this data to Google (upload all of your images to Google Photos) and they'll gladly help you sort it.