Overall, a great quality product from Marmot.  Note: (and I wish I had gone to marmot's site).  The Medium is really a large.  I normally wear medium coats (Columbia) , shirts and sweaters, but this was huge.  Marmot's website has the dimensions so I'd highly suggest going there first.  I am 5'7 and this was fine through the chest and waist but the arm length (34") and torso is too long.  The small would have been too tight.

I was contemplating exchanging this for the small but: 1. This item seems to be sold out in any decent colors 2. I actually like the larger size to layer underneath it.

I've taken this on 2 trail runs so far.  Both in the 18 F range.... one at night and one during a sunny afternoon.  First, the quality of this is amazing and worth every penny.  It is heavier than a mere "soft shell".  A long sleeved running thermal shirt and a tech T-shirt had me sweating 15 minutes into my run.  I do have to say it does breath well but is much warmer in high intensity activities.... 2 layers under this was plenty down to 16F.

Highly recommend... would have 5 stars if  it was not sized for an orangutan.