I was very pro VAR pre ConFedCup. However, VAR wasn't a great success in the tournament. I only watched the German games vs. Cameroon and the Chile final. In both games VAR decisions took too long. Furthermore, there was the big blunder in the GER CAM game, with the ref missing that he booked the wrong player initially. Also he got it right in the end. Furthermore, the ref was pressured into watching a replay by the Chile players towards the end. In general the whole VAR process was not optimal nor was it transparent. This may have been because it was implemented badly, because the refs were prepared badly or because the refs were generally substandard.
Honestly I don’t know whether VAR will be a success in the future and how it should be implemented. A lot of ideas were mentioned to change how VAR should work (external ref making the final call, one or two calls for VAR per team, putting the communication between ref and external refs on speaker for more transparency, giving the ref easier access to the video via a handheld device, etc).
What I don't get, is why FIFA tested this in the ConFedCup. What FIFA should do in my opinion before showcasing it at the world cup is testing various implementations in confined environments and comparing it to how it should work. They should chose some leagues with sufficient infrastructure (like the second leagues in the UEFA Top 6 countries) and check how the different implementations pan out regarding decision making, disruption of the flow of the game and other objectives which haven’t even been discussed (costs, fan acceptance, increase/decrease in interest/value). The testing has to be done over an extended period of time of at least one season, since we haven’t even looked at mid to long term trends yet. Will refs get better using VAR? What will players or coaches do to cheat/game VAR? Will refs change their decision-making (don’t call close offside situations) because they can undo some wrong calls (offside not called wrongly) but can’t undo others (offside called wrongly)? Until different implementations haven’t been tested and compared we can only speculate how each of them would pan out.
If FIFA is really into VAR, presenting such substandard implementation isn’t doing them any good, however.