I got this top because I found some issues with other wool base layers. Weights under 200 are too fragile, but over 200 tends to be to hot and slow drying once sweat soaked . My Smartwool medium weight, while a fine top, tended to lose its shape after 3 days in the field and the seams on the arms tended migrate from under my arm, around the inside, till the seam stopped on the top of my wrists.
This 200 weight Icebreaker solves all those issues. The neck never loses shape and the body never wrinkles or gets loose due to the elasticity of the fabric. The sleeves and seams stay put and the whole shirt is as good on day 3 as day 1. It still does not stink in the field. Its light enough to not be prone to sweating out by exertion, but warm enough to wear alone in cool weather.
I had some concerns upon purchase. There were old reviews of this shirt that mentioned heat transfered label on the shirt coming off with wear, the shirt does not reccomend machine drying, and the sizing, which is based on chest size seemed off from other clothes. The shirt now uses a high quality embroidered logo on the chest so the heat transfered logo is no longer an issue. I have continually machine washed and dried this shirt and it holds up even better than Smartwool, which reccomends a machine dry. Finally, the sizing is dead on if you use the chest sizing. At 6'2" 205, I wear an XL or sometimes a L in loose clothing. My chest size is exactly 46" which Icebreaker says is XXL. While different than other manufacturers, their sizing recommendation was dead on. This shirt is tighter than the Smartwool medium weights but not Underarmor tight. The ad picture is an accurate representation of fit if you follow the sizing recommendations. MEASURE YOUR CHEST BEFORE ORDERING. Once you get the shirt, cut out the label on the inside of the body, its annoying.
All in all this is the best wool base layer made. Better than Smartwool, Patagonia, Minus 33 degrees, or anyone else.