I bought the white knit and its not sheer at all. Its a comfortable thickness. It's not overwhelmingly warm when you're inside but not scarcely thin when you're outside. The only thing I would say to look out for is if you have a chest that is bigger than US B, it will be extremely short and you'll want to wear a high skirt with it.
I have a C in US and F in KR/JP so I can only wear this if I have a skirt to tuck it in to :)