I absolutely hate them. I hate not being able to read a text and respond to it on my own time. It doesn't do anything for face-to-face characteristics whatsoever but it does put pressure on me to respond. If it's that urgent, call me, or just make plans with me to get coffee or something.

KakaoTalk [0] does this and I end up just having way more notifications because I don't want to leave someone "on read" until I get around to responding. Actually, many, if not most people "read" incoming texts via the preview from notification centers so they can read it without feeling like they have to respond right then.

I hate how it conditioned me over time to check repeatedly to see if someone had read my text or not. You could argue that they might've just wanted to respond later, but that's not the "culture" of how kakaotalk is used generally. I have some friends that take anywhere from ~3 days to 2 weeks to respond but they don't open the text until then. I vastly prefer imessage or other apps now simply because I can toggle off read receipts.

[0]: kakaotalk is the messaging app of Korea. I don't think I've ever had someone send me an actual text or phone call outside of KakaoTalk. Line (Japan) is similar and also has read receipts unfortunately.