It's ad and tracker/malware blocking at the network level!
This means if you install one on your router, anyone who connects to your network will be spared from all the crap that it blocks. This is especially handy in households with kids who don't quite get the whole "you really need to be careful what you click on" thing yet.
And it also blocks mobile ads (Android and iOS) and smart TV ads! Which is not quite as effective as avoiding a "smart" TV altogether, but some folks have already made that mistake and spent the money so this would be a good patch.
For some people with lower-speed connections this will also dramatically improve their perceived connection speed by freeing-up the drag on their bandwidth that ads and trackers normally cause since they are blocked at the DNS level instead of by a browser or their device's firewall.
The project's main site:
A highly-caffeinated and somewhat ironic video about how to set it up:
He's kind of accidentally showing us the future of ads since he explains how to block them in a video that basically functions as a de facto ad, lol.
This is not a simple plug-and-play device (yet!), and takes some technical skill to build and install. So if you can't or don't want to do it yourself, find a geeky friend who can since as soon as they hear about it they'll want one for themselves and they'll owe you one for turning them on to it.