I think this match very neatly proves why VAR is both a good thing and currently implemented badly.
If Liverpool had scored the penalty, VAR would have facilitated a swing from 1-3 based on wrong decisions to 2-2 based on correct ones. That's a significant impact and if Liverpool hadn't been so poor as to collapse anyway, it would have been game-defining - and although I don't thnik it's currently the case at Liverpool we can all think of managers who's jobs have been saved or lost based on cup runs. I'm baffled how getting these decisions objectively right could possibly be considered a bad thing for football or refereeing standards in isolation.
But, as many have pointed out already, it has significant flaws too. Time used up carrying out reviews is clearly not being added on correctly, it looks absolutely rubbish to those in the ground and not much better to those watching on TV at home, and perhaps most importantly to those of us on this forum, it's coming dangerously close to affecting the actual decisions referees are making.
The last point I think will be less of a factor if a review system is implemented - referees won't want to have a manager overturn their decision, so extra incentive to get decisions right rather than taking the "safe" option that can be easily reviewed. Perhaps we need to consider an independant timekeeper as well, as referees clearly can't be trusted to stop their watches correctly at the moment. And the issue of why replays can't be show in stadiums and we can't be allowed to listen to the referee's communication is a much bigger one than just VAR....