Pretty much every time someone sees it one on one I get a reaction. Not too many people have been in that situation (sadly) so most of the reactions I have gotten have been in locker rooms. There have been guys who wouldn't stop staring, who would get hard and start stroking their cocks in front of me (I assume because they wanted me to do the same), and guy who would slip me their number of email address while I was getting changed.
With women, my numbers aren't too impressive. My first girlfriend cheated on me several times but kept coming back and telling me about how the guys she cheated on me with were much smaller than me. It lessened the hit to my ego, but I'm think I was probably more of a romantic than her. Still, when we had sex, we were each others firsts, it was painful for her and she cried and got upset when I stopped, because of her crying.
My second girlfriend was similar. She didn't cheat on me, but she had problems having sex with me. She was obviously in pain and I kind of gave up having sex with her.
After her I found a woman who could take my cock and enjoyed any pain she felt. She told me about how big it felt in her, how deep it was. She would talk like that and it would make my cum faster than I would have liked.
The most recent woman I was with, we didn't have sex, but she did give me a handjob and a blowjob. She wasn't very experienced and it was pretty obvious, but she did comment on my size. Unfortunately, her comment was that she couldn't keep sucking my cock because it was hurting her jaw. She said that after only a couple of minutes, so I'm not sure whether she was being honest or just didn't want to do it.
Online I get comments on my cock everyday, on this site and on the few other sites I have my pics. There aren't too many things that get me more turned on then someone commenting on my cock.