Perfect for layering.  Ordered 4 in medium & washed them in cold - no shrinking problems.  I have fairly broad shoulders, long arms & torso.  I'm 5'6"ish. (Everyone thinks I'm taller than I am.)  Anyway, love these shirts.  Just ordered 2 more for myself, 2 for my daughter (XL) and 2 for my BFF (S.)
In London I put them under fitted turtlenecks or cute cardigans, or wore all 3 layers at the same time.  I was afraid if I went up a size it would get bulky.
Have worn them solo too!  Great with jeans or tights.  They are form fitting but not in a way that shows every ripple, bump, or love handle.  At 45, I have embraced my little pot belly.
I like the extended length of the sleeves and waist (which covers my lower back tattoos,) so I'm getting more to wear under my scrubs at work.  My BFF is a nurse and I know she is going to loooove these too.  She is petite & I buy her clothes all the time.