I think it's entirely a good thing (in theory). Correct decision should be made every time but, also, you should cut out defenders stopping playing and putting their hands up in the air for offside, then berating officials if/when a goal is scored. Quite literally a case of play to the whistle.
Will be interesting to see if every single offside is reviewed retrospectively, though. What if play goes on and results in a throw-in to the defending team. If the attacker was offside, will a free-kick be given instead? etc. etc.
Also, VAR doesn't replace the officials. It's an additional official, reviewing incidents on a screen. Technological advancements and all that.