I see this question quite a lot, and I can't answer for all women of course, in fact, one could say that I can't answer for any women at all. But none the less, I have had experience with several women in my life, and they've had a wide range of reactions to my wearing panties. Please note that these are not all women I have been intimate with, simply women who had some idea that I wore panties.
4 - Giggled and laughed (To be fair, for a couple of these women it was simply a matter of me pulling down my pants in a darkened corner of a bar and letting them see. By way of explanation, I was young and stupid.)
2 - Reacted in disgust (Mom and my first girlfriend. This is a good example of why mom isn't always right and why it's sometimes best that you don't marry your first love.)
3 - Kind of hesitant at first, but came around in varying degrees. These three were the middle ground and I am pretty sure some of them may have preferred that I didn't wear lingerie, but they didn't make a big deal out of it.
2 - Quite enthusiastic. Purchased me lingerie as gifts, were happy to experiment with lingerie in the bedroom.
1 - Loves it, buys it for me, buys matching sets for us, loves to make love with me wearing lingerie as much as she likes making love when I'm wearing a policeman's uniform costume. (This lady is now my wife. I know they say sex isn't everything, but the trials and tribulations of marriage are much easier to go through if you have a hot and adventurous partner.)