Lovely colors and quality -- just wish my son would wear it!
Sadly, while my son agreed to try to the shirt on, he has since refused to wear it.... He says it itches him a bit and doesn't feel as soft as his other shirts. I don't personally find the shirt to be itchy, and it feels quite soft to me -- but my son is VERY sensitive about how his clothes fit and feel.
Knowing how my son can't stand tight-fitting clothes, I purchased a size up. My son just turned 4, and I got the size 116 (5-6 years), and I was pleased that it was a bit roomier -- but my son didn't swim in it. I think the size would work well to still fit under t-shirts or other over-layers and yet not be too constricting, IF my son would ever agree to wear it.
This is just a matter of his personality, his general ongoing clothing aversion (he still prefers to wear mostly nothing but a t-shirt inside the house) and his sensitivity to how clothes feel on him.
I think this shirt would make a great underlayer -- especially if your child is more open to new clothes. I'm crossing my fingers I'll be able to try again this coming fall and winter, and maybe he'll have grown into a different state of mind.