Personally, I really only care about 'passing' as cis for safety reasons. If I'm in a safe and accepting area, and people can guess that I'm trans, I'm fine with that as long as they're respectful about it and don't treat me like a guy. I'm still trying to sort out whether I'm female or fem-leaning non-binary though, so my feelings on passing might change over time as I figure myself out.
I have been on HRT for almost 4 months, and I've reached a point of looking much more androgynous than I did before, and I'm really happy about that! I don't know in the long term whether I'll feel better looking completely female or slightly more androgynous, but for now at least, not being assumed male all the time is so validating!
As far as how I've been treated looking this way, I have had a few people give me a slightly puzzled look, or sort of stare at my face for a bit, as if they're trying to figure me out, but so far no one has been outright mean about it or anything. On average though, people are generally much friendlier towards me now than they were a few months ago, which I'd guess is due to me being happier and more outgoing now that I feel better about myself and my appearance.
As some others have mentioned, I've also found that voice, posture, and mannerisms make a big difference. I live in a fairly tolerant area and I definitely wouldn't attempt this everywhere, but even with baggy male clothing, no makeup, and a minor beard shadow, I can be gendered female pretty reliably if I use my more feminine voice and mannerisms and do so with confidence.