Indeed, after a 30 to 40-year hiatus, the kickback hub is back! I have an old Bendix 2-speed kickback hub on one of my bikes.
I love it. It's really the perfect hub for a simple tooling-around-the-city bike. The only problem with mine is that it is four pounds. I assume the new version is much lighter.
The way it works is that every time you back-peddle it switches between low and high. And it has a coaster brake. You can switch gears without braking but you cannot brake without shifting. It kind of sounds like a pain in the ass, but it's not.
Why is this this good? First of all because two-speeds is perfect for 80 percent of your biking needs. Second, basically I use the low gear for starting (sometimes) and for going uphill. I use the higher gear for everything else. And how many other two speed bikes do you know? This gear has no cables, no handles, no derailleur, nothing external, no nothing that needs maintenance or can break. It's the perfect city hub.