The jacket is perfect for trail running and hiking in the fall/winter. I'm 5'9, 155, got the medium and it's a perfect fit. It's a little longer than other soft shells I tried, and still slim. From what I've found, this is the best jacket for outdoorsy activities in cooler weather.

Looks like it's getting some cred where deserved:
http://outside.away.com/outside/gear/buyers-guide-winter-2009/essentials-winter-running.html

This jacket is very lightweight and breathable. It stretches with your movements and gives just the right amount of wind resistance. It is both stylish and has great functionality. Since it has no insulation/lining the jacket makes for a perfect outer layer when running, hiking, or for use on those cool days in the city. This jacket even performs well in light rain thanks to the Deluge DWR finish. The Traverse Jacket is cut for tall and thin folks, so remember that when picking-out your size (slim fit). Overall, the Patagonia Men's Traverse Jacket is the perfect lightweight softshell jacket for active pursuits during 3 seasons.

Love this jacket....This is a great lightweight soft shell. It stretches well and breathes great as well. It's got a mini zip cord to snug up the bottom and a fleece lined inner collar to minimize chafe. I also like the arm cuffs are nice and sung on the wrists and the pockets are soft lined to warm up your hands if needed. I use it for cycling on cooler, slightly damp days (repels light water well) and on cooler trail runs when I know I'll be wearing a coat the entire run.

I've been looking for a very lightweight soft shell jacket for two years ... but everything I saw was either nylon (too clammy) or weighed a pound or more. This jacket is only 10 oz, highly water resistant, and it breathes very well.

I took it on the Teton Crest Trail in Sept (great to cut the chill in the mornings) and on several October day hikes in New England. It won't replace your rain shell ... but it's the most versatile article of clothing in my pack.

this is one of the most versital short jackets I have worn. it is also cheaper than their guide jacket. I'm tempted to call it a windshell but it has more coverage and stretch than ripstop nylon.