given the amount of money involved in football now, VAR was inevitable, and needn't be a bad thing. But unless and until it is applied a) sensibly and b) consistently i think it's not doing itself any favours.
I want to see the calibrated line abolished - or made the width of an average foot. Giving offside for an infraction of a millimetre is ridiculous. If the naked eye can't see it, IMO, if the decision for offside is given because of a calibrated line, it shouldn't be offside and the decision given in favour of the attacking side.*
IIRC the rule is that VAR is used in situations that could affect the outcome of a match: red cards, offside decisions and potential penalties. Watching PL matches (and increasingly BL matches) some refs seem so scared of goals that they want to refer each one to VAR (or the VAR operator is so scared of goals they insist on looking at every one). It makes a match tedious if you don't know if you can celebrate a goal or not. again, i am all in favour of tending towards the attacking side where there is a tough decision - it rewards attacking football and IMO that is never a bad thing. And don't get me started on the ref going to a pitchside monitor. Just no. If the VAR can't decide, it should be up to the ref to go with his own decision. Whether that's his original one or he's changed his mind: if the Ref calls it, that is it. Ref decides, he is in charge of the game.
Or they do it like tennis: each coach has 2 challenges per half, and if it's upheld he keeps his challenge, if not upheld that challenge is gone. And VAR keep their beaks out except in seriously egregious actions or clearly batshit decisions.
*tbh i used to be scathing of the USA soccer requests to either do away with offside or to have a 25 yard line to help the refs with their decision making. all in an attempt to increase the number of goals per game. Now I'm more prepared to listen to the former (not the latter) view.