Pros: The technology works. The fog is quickly cleared with a press of the boost button. Fog-free all day.
Cons: Don't fit over eyeglasses. A bit too large with SMITH helmet, but this is also true of other goggles with this helmet (between helmet and nose).
I agree with everything the other reviewer says. They work. They don't fog. The fit may or may not be good for your helmet. The SMITH helmet I have is problematic for my other goggles (SCOTT goggles) and the ABOM goggles. There is not quite enough room between the helmet and the bridge of my nose. But this is a small anoyance, not a major issue.
I have another racing helmet (BOERI), and the goggles fit that helmet better.
They would be PERFECT if they fit over my eyeglasses, and also fit the SMITH helmet.