Edited to remove “booking”. But as "“a partnership with Google is required” to appear in Google Flights", (and it hides the best flights, likely because of lack of such a “partnership”), I would consider the entire service an infomercial-like advertisement.

Google Flights' list of booking options is much more reliable and trustworthy than the sketchy OTAs that offer slightly discounted flights and then conveniently disappear with your money if you ever need customer support, or worse, levy bullshit fees to do things that would otherwise be free if you booked through official channels.

If you want to screw yourself over for $20 savings, use another flight search engine. I'm quite happy with Google Flights myself and don't need it ruined.

It provides a better search than, say, united's search. Especially if you are looking for partner-flights or more interesting layover-cities. But it also doesn't include southwest flights (most aggregators don't) which often have the best price for my home airport on short-hauls.