Bloodied was a Condition in 4E that indicated a person was at or below half hit points. It allowed for some interesting abilities that fed off of the mechanic; such abilities as a Bloodied creature being easier to hit or if you were Bloodied you did more damage. 5E did away with the Bloodied Condition. I still use it but in a very watered down version.
4E Bloodied required an extra step of math, especially as it pertained to the monsters. Players would be constantly asking if a monster was Bloodied. I can see why the more streamlined 5E got rid of Bloodied. However, one way I used Bloodied in 5E was as a signifier of how damaged a PC was. A PC down only a few hp could have some minor cuts and bruises. What was to show that a PC had taken some serious wounds. For this I used Bloodied.
I try to be as narrative as possible. If a PC ask the health of a PC instead of giving hit point numbers I simply said if the PC was Bloodied or not. Narratively, I am telling the player that the PC has taken some serious damage. I kept this simple term for 5E.
For my 5E games, I break down all visible signs of player character damage as Healthy (undamaged), Damaged (above half hp), Bloodied (at or below half hp) and Dead.
Thus I never give out numbers. The players can guess at exactly where each PC is, without knowing the precise number. This most comes into play when the healers are deciding who to prioritize for healing and how big of a spell to cast. For my group it adds a slight element of risk and "haze of combat". And it helps a bit for immersion as we talk less in numbers and more as to what the PCs are seeing.
I wouldn't mind seeing the Bloodied Condition come back for 5E. I think it allowed for some nifty combats maneuvers. However, for now, I'm using this lesser version of the condition.