Especially the chin straps. It's nice to have a set of chin straps that aren't so heavy. The helmet itself is light and well ventilated. The support cinch on the back doesn't get in the way (even if you have lots of hair, like me). And the pads hold in the sweat well.
I had to block a few outreaching branches with the helmet on my last ride. Solid smacks on the noggin, too. To my surprise, nary a scratch on the plastic. I consider that a good sign.
Will I buy another Hex if smash up this one? Yeah, probably.