personally i have experienced it once on twice being on both the receiving and giving out end....
Sometimes you hit a dude and see blood but no hitreg whatsoever, it tends to be annoying but no that bad since it happens maybe 5% of he time, its very rare. Also sometimes when i get shot by a sniper i hear headshot noise and was like wtf, how am i not dead, i heard that headshot noise!
Also sometimes when you kill an oke he freezes and moonwalks for abit before he's dead, i asked Xerowing about it, its a backend/pb related issue, many of my clanmates were very concerned, especially R4C3 but i explained to them that DICE were probably aware of these issues and since they are not on some deadline to release a game every year they'd fix it since they'd know about it and have the time to address it
other than that, i think a great game is on its way and its good to see that DICE LISTEN to the community!