This pattern plays a big role on mobile devices, where vertical screen space is scarce.
I suggest using Chrome on iOS (perhaps on Android, too). The way the URL bar behaves is exactly this feature, but feels very natural and gives you a great, full screen reading experience.
My guess is it works a lot better on mobile since scrolling happens much more often and is more intuitive than on the desktop.
This way it becomes second nature to swipe the content towards where you suspect your desired element is – and the URL bar is always at the top, reachable within half a second no matter how far down you are.
Here’s how it looks like in Safari:
Definitely less so on the desktop, where we not only have the screen space available to show chrome and give a good reading experience, but where scrolling to get to crucial elements feels very forced.
In case you want to use this feature in your project, there’s a jQuery plugin for that: http://eduardomb.github.io/scroll-up-bar/