Sadly no longer written by John Siracusa, but still a good read: Ars’ Max OS X El Capitan review.
Really, this is the first time in several years that iOS and OS X have felt like they’ve gotten (and needed) the same amount of attention from Apple – both get to spend a release in the slow lane as Apple puts its marketing muscle behind newer platforms like the Apple Watch and the new Apple TV. Like iOS 9 (and Mountain Lion, and Snow Leopard), El Capitan is about refinement. Yosemite’s big statement was “This is what OS X looks like now.” El Capitan’s is a relatively meek “Hey, I have a couple neat tricks to show you.”
To work, both use code injections, one into Finder and the other into the Terminal app, and Apple has blocked this behavior while not providing any API or extensions to more of the system.
The only way to get these apps to work, is to disable a security feature while in recovery mode. Hopefully, the developer will find another way to do them.