I recently purchased this jacket for running (Nov '11.) I tried it on immediately and discovered there are not only thumb holes as described, but there are mitts inside the sleeves! Nice touch. Description doesn't mention this, but this is nice to have when my hands are feeling a bit chilly during the first mile or two.
I'm 5'9, 140 lbs, and have size M. The arms are long enough for me (my biggest concern). They are a little more snug if I chose to use tuck my hands into the mitts, but still long enough.
This is perfect for my 10-30°F runs outside. Anything above 30°F and it's going to be too warm. I haven't tried running in it in anything less than 15°F yet. I wore this to the store on a 40°F breezy night -definitely too chilly to wear as just a jacket while not running unless it's about 50° as the wind blows right through the sleeves.
Stretchy fabric on the arms, thin quilting on the torso. I'm amazed at how light this jacket is, and yet keeps your core so warm. I usually end up unzipping the jacket about 6-8" before my run is over.
Only downfall to this jacket is the armpits get rather stinky and it must be washed about every 3-4 runs. It would be nice if North Face used a different fabric in the armpits so it wouldn't require such frequent washings - perhaps something with silver?
I ordered the exotic green for visibility purposes - it's really more yellow than green, which is fine by me. My running friends all love it - looks fabulous on.