Short verdict: Haters to the rear. It’s a good movie.
It’s not just a good movie, it’s a good genderflip AU, in that it doesn’t just paste the guys’ names and roles onto some female bodies actors and call it a day, it actually asks itself things like, “If this basic character type had been born, raised, and socialized female, what would she be like?” and “What sort of public reception would these people doing these things get if they were four women and not four men?”
So the Venkman character as played by Melissa McCarthy is not the at-least-50%-charlatan that Bill Murray’s version was; and the four ghostbusters, instead of getting citywide acclaim after their initial successes, are treated in the media (with the connivance of City Hall and Homeland Security) as being either frauds or delusional or both.
An all-male remake would have just been putting a new coat of paint onto the chassis of an old classic; by going with a true genderflipped version, the creative minds involved managed to take their inspiration from the old classic and use it to say some new things. And the haters were right to be scared of it, because – in its lightshow-with-explosions kind of way – it’s pointing a mocking finger at the very sort of male privilege that they’re so obnoxiously, and anxiously, defending.
So yeah, go see it. And stay through the credits.