As a fan of wool items, I've had my eye on some merino shirts for a while now, and had identified Wool & Prince from the 100 day challenge. After getting over the fact that I just don't need as many shirts these days given my new hybrid work schedule, I wanted some versatile shirts that didn't wrinkle, didn't smell, and didn't need to be washed often.
Overall, very nice shirts. I'm 5'9" with a slim/athletic build. I got the slim/medium. Body fit is good, hem length is good if you want to leave it untucked, but honestly the sleeves are probably a half inch too long. Not a big deal for me since these won't be worth with a suit, but definitely something to keep in mind. The lack of sleeve length is the reason for the 4 stars and not 5.
You may experience itchiness at first; I get this a little with some wool coats. The type of soap you use will help - Woolite or Dr. Bronner's seems to work best. After a couple of washes now (one right out the box), the shirts feel nice and soft.
I'll probably end up buying one or two more; the only issue here is that given they can't make a "white" shirt, you mostly only have a bunch of patterns to choose from once you're done with "blue."