I'm a believer.
Shorty turned me on to this thing a year or two back, but I was stubborn and continued to clip in at the belay with a sewn runner or by girth hitching the rope. I finally conceded before a recent trip to Red Rock, and this thing is great. The fact that it's adjustable and still so secure (where a daisy is pretty easy to kill yourself with) is the big turn on for me. The only downside I see is that it can be a bit bulky when you have alot of gear racked on your harness.