I've used the heck out of them since receiving my set and I'm blown away. They solve some of my biggest issues with drilling holes. They seem to significantly reduce the burr on the back side of a hole, they all but eliminate pilot drilling (though you can still drill a pilot hole if you choose to), when enlarging an existing hole, they don't inadvertently grab too much material and mangle the hole (or bind up the drill), and perhaps most importantly, they actually make round holes. I try to use a drill press whenever possible to keep the drill bit centered and make round holes but I swear I get 3-lobed holes even in the drill press under some circumstances using traditional twist drills.
I'm not someone who ever learned to sharpen drill bits so I usually just replace singles when they're worn or broken (my metal supplier has a complete rack of norseman singles right by the checkout counter). If Astro would sell singles of these, I would be in heaven.