A little hard to explain, but in GENERAL, a "rolled" shoulder (either up or forward) is not good. That places the shoulder in a weak and potentially injury prone position.
The shoulder moving in towards the bow/string/arrow is a flat, lateral movement NOT a rolled movement. Generally, though, IF you keep a "down and back" thought for the bow shoulder, you will have what you want.
I find that motion is hard to explain in typed words and quite easy to show/demonstrate in person.
Arne