I ask a passer by (like a colleague), and have them done in 5 minutes. But if you're on your own, or surrounded only be eejits (or at a race meeting) then it can be a godsend to have something like this.
Personally I prefer the human touch - they can tell you to pump, and to stop pumping when the air is gone or the new fluid is coming. On your own you just have to pump for a bit, get out and check, get in and pump a bit more. It's when you get out and discover that a pipe has slipped and sprayed brake fluid over your paint that you wish you had a real person.