The company thought introducing its first consumer product on April Fools Day would guarantee them a lot of coverage, and it has. But the service is legit, up and running and ready to rock.
DNS lookups, which translate domain names to IP addresses, are performed for every internet transaction. The default DNS provider is whatever network you're connecting to, whether it's your ISP at home, your company or free Wi-Fi at your favorite coffee shop.
While your internet connection may be encrypted, DNS requests are not. So whoever is providing your DNS knows every site you've visited and U.S. providers are free to provide that information to whoever they want, thanks to the U.S. Senate.
Cloudflare's 1.1.1.1 DNS is free, claims to be the fastest and is committed to privacy. Cloudflare promises to not write DNS logs to disk and to wipe any logs after 24 hours. It also has retained KPMG to annually audit the process and publish a public report.
Changing your DNS is best done in your router, which will take care of all devices using your network. But for devices that visit other networks, you'd best get into the device's network settings and change it there. Cloudflare's 1.1.1.1 site has instructions for iOS, Android, MacOS, Windows, Linux and routers. All except Android, which only lets you change DNS for a static IP address (gee, I wonder why...) make the process easy.
More info in Cloudflare's blog post announcement and the accompanying post providing the details on Cloudflare's 1.1.1.1 DNS resolver service.