I did not always wear it until I read my first Laurie Cabot book. She is so very inspirational to me, how she has no fear of opinion and lives her Witch life just like everyone else lives their lives. Unfortunately, my situation is not quite like Laurie's, so I do make some concessions. I wear it under my clothing. Otherwise, when I am out in my personal life, I very proudly wear in out and upfront.
Reactions vary as widely as types of people.
On the average, I would say most people really don't care. I have actually had people ask me if I'm Jewish and comment on my Star. Everyone has to make the decision for themselves if it is safe for them to wear the Pentagram out of their clothing or at all. For awhile, I used to keep it in my 'personal items' pouch in my purse, so I did still have it on me at all times. Yes, I do wear a pentacle necklace in public.