Bought this for a backpacking trip in the Sipsey Wilderness in northern Alabama one week before Thanksgiving 2009.  It held up nicely for what I needed and I am very pleased with it for what I paid.

The stitching seems sound and the quality of the material is just fine.  There is a lot of stretching room horizontally (fat/thin), but very little stretching available vertically (tall/short).  I buy my button-up shirts with a sleeve length of 33"-34", and the large fit my sleeve length perfectly (assuming the appropriate length sleeve will not bunch at your wrist).  There was also PLENTY of length on the shirt to ensure that it stays tucked-in (nearly an extra 4"-6" longer than typical undershirts).  The collar was not tight, but it was not loose, either.  It is labeled "Mid Weight" but I would say that the material is mid-to-light in weight.

Overall, I am very pleased with the purchase, and I would certainly recommend it to others.