I have had the OR Ion and used it for the last 10 months and think it is "da bomb". Never having had a windshirt prior to the Ion I cannot make any comparisons but find that, over a base layer, I am comfortable at much lower temps and higher winds than I would have thought possible with such a combination and that, as far as I can tell, the windshirt is breathing out the majority of my sweat vapor. Living in the Middle East I have yet to be able to really test out its function in the rain. The hood is very nice with a good brim and ability to adjust just right but I haven't yet figured out how to set it so the side drawcords stay snugged tight while running.