In my experience playing Lifeweaver(100 hours). I have simply come to the conclusion that LW is just a high skillcap champ. You have to know positioning, and champions abilities and cds in order to make the best predictions on when to pull someone. I feel his pull is what set people off more than anythig in the game probably. Being a very experienced LW myself, I get irritated when someone pulls me unecessarily, ESPECIALLY when I was about to kill someone and take an objective. I havbe been amazingly saved though at times and am irritated initially then was like wow thankyou. I have never once been complained about when I pull people. I have had people initially complain when I picked LW, but I have only ever had people sing praise about how good I was compared to what they had come across before. He is still newish and not often used. I think people just need to play him more and learn better how to use him.
-Just because someone is low does not mean they are going to die. They might be about to crush the other team in a combo attack. You need to be aware of what ults your team has, where everyone is, where the other team is, their ults, etc. Pulling your rein out if he is kind of low when he has 3 people with him including the other healer against 1 or 2 people on the other team isn’t really necessary unless it’s a bronze moira whose oblivious to healing and rein has like 10hp lol. Maybe you have a lucio who is 1 second from ulting. You should absolutely always pull someone being charged by enemy Rein 
Most poeple are not aware that being pulled makes you immune to damage. I have pulled people with full hp right as a junk tire blows up on them to save their life. If someone has 1 hp and are ultd by a dva bomb they won’t die in the middle of a pull. Example: Twitch
-Positioning matters. You should always try to have good positioing in general as a player, especially as a healer, but as LW pulling someone it probably matters more at that moment than ever. Defensiviley you don’t just want to pull someone from one danger to another. Sometimes it can’t be helped and the attempt is nice, but you risk dying yourself pulling someone and the danger to yourself. Offensively, you again need ot know the cds and ults of who you are pulling and what they can do in that spot you are pulling them. You could just be killing them with bad positioning. I almost never pull someone offensively unless it is VERY OBVIOUS they want it to happen, or have asked for it.
-His healing range is MASSIVE. You can heal farther than anyone except scoped ana, but you can also arc your heals over walls and stuff which ana can’t do. The only annoying limit to his heals in my opinion is that they don’t go through barriers. When your team pushes past enemy Rein, Symm ult, Winston barrier, etc, not heals are going through.
-Lifts. Lifts are useful obviously, but not always just for you. Placing them so dps can shoot over walls they have no access to any other way is useful. Very useful things I have done with lifts is when enemy Mei walls off a teammate to be slaughtered, lifting myself over and pulling them back; When enemy Orisa ults, I drop one under her and away she goes hitting nothing and my team is in shock, same with enemy reaper ult although he can slowly move off and sometimes get 1 or 2 people instead of a team kill; when enemy Rein ults my team I always pull someone, and toss my lift under someone else to ALSO get them out; when enemy Ana sleeps someone, lift them away. There is just so many useful things you can lift for. Almost forgot, his lifts can take a bomb for you. If you hear a junk tire or dva bomb coming, you can use oyur lift and if it blows up under you, the lift will die but you will take no damage. Kind of like a Bap immortality.
Closing this random not completely thought out post with a few favorite moments:
Pulled my hog, who pulled enemy hog, who then pulled my hog.
Simple save and lift Kiriko
Saved ana at last minute while OVERTIME is ticking then jumped downmyself, and lifted myseelt for rein to get there. We won even htough our overtime ticked to 1%.
Bastion ultd by enemy Rein, Pulled and lifted to safety.
