Eh, earlier Van Gaal was better than the Van Gaal we had.
I don't hate possession based strategies per say, it's good to see your team 'in control', and there's nothing quite like a perfectly organised and balanced possession based team in full flow.
A lot of criticisms come from the worst of possession based football. A lot of time under Van Gaal we passed sideways and backwards indefinitely for entire matches, having the ball for the sake of the ball while offering nothing ourselves. It was deathly boring and not effective at all especially considering the players at our disposal.
Meanwhile you get teams like Pep's Barce.
It's one of those 'all or nothing' things. Possession based football is either beautiful or dull as dish water.
Generally I liked Van Gaal and have no ill feelings towards him. He has a clear defined strategy that he implemented, but he should have developed it beyond what he did rather than just let it linger as stale as it was. He got the players to play a base level possession game, now develop that to a progressive possession based game. And he was quite stubborn with some things for example 'my captain always plays' etc.
Right man but with his flaws, wrong time.