Pros: Comfortable, sun protection, ventilation.
Cons: Can't think of one.
I haven't tried the helmet yet (got it new off eBay for $88), but just wanted to respond to sanigene's criticism of the helmet due its lack of a "goggle gasket". One of the reasons I bought the helmet is that it has what Giro calls a "Vertical Tuning Adjustment", which was developed precisely to eliminate the gap between the goggle and the helmet and nose pinching from the goggle pushing down on the nose. Check out the video on al the adjustments for this helmet on the Giro web site - http://www.giro.com/en-us/products/snow-helmets/g10mx/
Here's a followup, since I skied a week with the helmet in Utah the last week of February, 2010.
First of, I had never skied with a helmet before, so I cannot compare to others, except that I tried several on before going with the Giro G10 MX. Second, I'll never go back to skiing without a helmet - it just felt great, skiing with a helmet made me feel more protected or bulletproof, or something. One day was very cold, and I wore a biking helmet "skull cap" under it that I've had forever and a nice neck gaiter and I was really comfortable. The other days I didn't wear a hat, and none of those were warm. The helmet was very comfortable, and I could hear other speaking easily, and had very good visibility. There was a small gap above one pair of my goggles, but they are nearly 20 yrs old, and the other pair fit perfectly. However, I decided to upgrade goggles, and went with the Giro Root, the one Giro recommends for the G10 helmet, so the gap issue will now vanish.
Overall, a great helmet.