This is a great merino piece. The 17.5 Micron wool and 150 g/m weight make it very versatile. I use it as a base during the coldest months, with a light layer during the cool months and often by itself during the summer. That's right, a long sleeve during the summer. It does so well at keeping the sun off and breathes so well that I can wear it in 95 weather without too much trouble, and it keeps my skin from burning to death.
Pros: Merino. Need I say more?
Cons: As others have said, the sleeves are a little long. The thumbholes keep this from being a problem for me, but it may bug others.