VAR is a good thing - if used properly (like it is done in Rugby for many years).
The WC Final was a very good example of what can go wrong with the current rule.
1. The full-blown dive by Griezmann prior to the first goal. No chance to review or intervene by the video referee, also no chance to challenge a review for Croatia.
2. The penalty decision. Reviewed after protests/challenge by several French players. In light of the wrong call just minutes before, it was a harsh if not brutal decision.
IMHO, this changed the course of the match significantly. Before France took the totally unexpected lead, Croatia was in charge and they came back once, but it a second time was too much to handle.
In the end, the refs were lucky that France scored too more (non controversial) goals, which took the discussion away from that aspect a bit.
This is all hypothetical and my personal take, I know, but that is basically why I cannot enjoy football so much any more. All the diving and cheating (and being rewarded for it) and taking time off the clock (and not being punished for that adequately) is killing the game, not some attempt to reduce the amount of wrong decisions or to eradicate unfair conduct.
That's my first and last post about WC 2018, another welcome distraction by the way for the local government to significantly raise the VAT as well as the statutory retirement age - a win-win for Gianni & Vlad