I haven't had a chance to test these on the mountain yet but so far:
They easily installed into my Revolver helmet. The cable is the perfect length to route the quick disconnect to either side of the chin strap making it easy to disconnect it when removing the helmet. Any excess wire was easy to tuck under the velcro pads inside the helmet leaving only the white disconnect exposed, can hardly tell they are installed.
The inline volume/mute was easy to connect to the earbud loop in the neck of my LibTech jacket and there is plenty of cable to use my iPod without looking like a dork. Sound reproduction is decent, the speakers are actually pretty large.
My only complaint: The volume could be a bit louder, but that could just be my iPod. It's loud enough just sitting here testing it but I'm not sure how well it will do with wind noise. I think it should be fine though.
All in all, Great product for the price. Would definitely recommend it to anyone with a Giro Helmet.