I've had it for one season now after using normal carabiners for about 6 years. It is a great belay carabiner to use with an ATC. I thought the inner clip was a gimmic, but I really like it. It keeps the carabiner from rotating on your belay loop when the rope is slacked, and normal carabiners spin very often. It's nice to know it's always on its strong axis and the darn gate doesn't get annoyingly snagged on the belay loop when loaded. I don't like fussing with a belay. It's one of those things you wouldn't even notice till you get this. Make sure you clip the inner clip over your belay loop because unclipped and loaded feels awkward. The spring gate is especially nice for the belay carabiner.
It's not so nice to clip into burly toprope anchor points since the clip side is so narrow, but I believe it was primarly designed for belay, and it excels at that.