I stopped caring what other people would think very early on. I despised the smell of the powdered formula we were supplementing our daughter with and fought my husband on at least one occasion to nurse my daughter when she needed it while we were out. I've nursed her during the picnic luncheon for my 10-year college reunion (held on campus in the middle of the day), on commuter trains on our way to New York, at the park, in the middle of meetings and even during a rehearsal for a choir I participated in last autumn. Sometimes I use a cover, sometimes I don't bother because she pushes it off anyway. I've become skilled enough that I can latch her without anybody noticing what I'm doing and I very rarely flash (if I do, it's accidental or due to a curious baby de-latching to look around at her surroundings.)
I have never once noticed a dirty look, and I don't really live in a 100% pro-breastfeeding area. However, I kind of project a "don't you DARE mess with me" vibe, and I'm too involved with my baby to notice the rest of the world.
It'll be really nice when the 2014 code goes into effect, but I think it should be a lot more explicit - like providing a non-restroom place to pump in each building if the corporate center is a multi-building campus. (I will pump in my car for the next child if our campus doesn't create a moms' room in my building because trying to find an open office with a locking door and no windows is too stressful.)