There are plusses and minuses and I think they need to be very careful how they implement it. We don't want to end up in a situation that American Football found itself in during the 80's where it seems almost every play was reviewed and therefore games took something crazy like 5 hours to complete.
Used sparingly, I think VAR is a good addition because it eliminates a lot of the diving. I can already see that most teams that are known for this sort of behavior aren't doing it as often because there is a much greater chance they will get caught.