Just bought a couple of these when in the Valley. Needed to hook some gear into my packs webbing and was looking for a light biner.

My buddy Jason has these on his whole rack and on his slings, he swears by them. As for me, these are about as light as they come and are very durable. I'm glad to have added a couple of these to a burgeoning rack of gear.

I love this biner. I use it on all of my trad draws and it takes a lot of weight of my rack. Also they are much bigger and still lighter than my BD neutrinos

I liked 'em so much I replaced my entire rack with them... Besides the obvious pros that have been pointed out by the other folks, this biner has about as strong a gate spring tension as I've used in biners. I like this because it makes it that much less likely that ropes, bolts, gear can escape, harder to vibrate open in a fall, yada yada. I also like that they are larger than other small biners. In practise, they are significantly larger than neutrinos and bigger still relative to nanowires (or whatever Camp calls their ultralight). I wouldn't be caught climbing ice with a neutrino, but I could do it with a superfly. The biner is just big enough to handle with gloves. I believe their only competitor is the WC helium. Buy the heliums if you can handle a few extra grams and a non-catchy nose means a lot to you. Buy the superfly to pay a lot less for a lighter biner.

If you MUST be light, then this is a very good biner, but with one flaw. The biner is so light that when used on the rope end of a sling, it will frequently orient itself in a position to cross-load across the weak axis. This tendency is extremely disconcerting, but the biner is great for pro-end work clipping wires, at belays, and for racking.

Taping the biner so that it is captive in the sling (in a sport climbing kind of way) might be a good idea if you want to use these with shoulder length slings.

Lovely biner, superbly light.
'full size' but barely; the 'inside corner' is a bit small for tripled slings or racking nuts.
The gate action is quite stiff and when really trying to get gear in fast, it's a handicap/stress compared to the similar Mammut or DMM biners, which are almost as light.