A must for one-bag packing
If you're packing light and going with only one bag, the Marmot Ion is a must. It's ultralight, and best of all, it rolls into a small bundle that fits easily in your pack or in your pocket. It stops the rain. It stops the wind. And it's stylish enough to wear out for an evening. An excellent price here. It and I are on our way to Europe.

Easy to take along, great to have when you need it.
Perfect for rest stops during cold wx hiking or xcountry skiing.

Great multi-use jacket
This was exactly what I had hoped it would be! Its very lightweight and can tuck into nearly any spot in my pack, or even in a large pant pocket. It definitely cuts any chill from the wind, but yet is not an overly warm jacket, thus making it perfect for those cool breezes on the summits during warmer months of the year when you dont need a really need (or want) an overly warm jacket. Additionally, it is stylish enough to wear even for "non-hiking" adventures around town.

Oh so light and packs small
The Men's Ion is ridiculously light. It also packs up as well as any jacket I've ever seen. It hasn't gotten cold yet where I live so I haven't used it with a midlayer but it seems to be perfect for that, as the one problem I have is that the torso is a little big and the waist is not fitted so it hangs loose. I am 6'1, 160 lbs and the large length and arms are a good fit. The material is not see through (I have the lava color) which is a big plus for me. It looks sturdy, but feels light. It blocks the wind but doesn't make you feel like an oven in the heat. I would recommend it.

good ultralight option
I bought the Ion windshirt for summer backpacking, and it seems to be pretty close to ideal for that purpose. I wore it while partially sheltered by trees during a brief thunderstorm, and it did a nice job at shedding a few raindrops. I mainly have it for a light layer to wear in camp or during rest breaks. The only criticism I have so far is that the XXL is cut so short in the body that it looks really goofy on a very tall man (I am 6'10"). This doesn't really take away from the functionality of the garment, but I probably wouldn't wear this around town as a tourist, because it looks funny. I would gladly sacrifice an ounce or two of weight for a little extra length in the body.