I think we all gotta admit, it's pretty trash.
Spoiler alert:
At the end, Grindelwald escapes, and there is no epic battle which I'm sure is what everyone was expecting considering this may perhaps be the last movie of the Fantastic Beast series. And plus, the first two movies (which were great) built up the hype for this (potentially) last movie, only for it to flunk so bad.
Honestly at this point, its probably best to watch the first two movies and leave the third one up to your imagination - anything is better than this very disappointing film.