It's a useless site. I hope no energy is drained from the superior ITA matrix tool.

• Google flights does not find the best airfare
• it lacks the expressive power of ITA
• scope of inventory is limited to common databases (no LCC scraping)

It has all of the shortcomings of ITA, and it lacks what ITA is really good at. And it introduces nothing unique. It's a completely redundant tool, so I won't be using it even if intl flights are added.

If you want expressive power, ITA software trumps.

If you want the lowest airfare, you have to use sites that are capable of multiple bookings (dohop or skyscanner), and you still have to check the sites that scrape the LCCs (listed here).