I personally find this film to be quite lackluster. The plot makes little sense, there were numerous times where the term 'Suspension of Disbelief' was strained to the point of hilarity, and the action sequences made little sense and were hard to follow.
One thing this film had going for it was the acting. Mads Mikkelsen brought a wonderful darkness and depth to Grindelwald that really made him pop, Eddie Redmayne was wonderful as always, and Jude Law pulled off a good young Dumbledoor.
I also enjoyed the aspects of the film which involved the Niffler, because come on, its the Niffler and therefor adorable.
This is where my praise for this film ends.
The plot makes...no sense. Things seem to just happen, and when teleporting wizards are stopped by a small, see through glass door, it really makes you wonder if the writers know what they are doing. People just get hit by powerful spells in the middle of a busy road, building explode, and books beat people in the middle of a plaza, and no one cares. The whole movie was saved by something happening vaguely off screen, for crying out loud! And the 'plan' that Dumbledoor has is so absurd and stupid that upon examination makes zero sense.
The Action sequences also suffered. Due to the lack of verbal spells, in fights things just happen. Some times they use their wands, some times the don't. At one point, Dumbledoor punches someone into a different dimension. It is really hard to follow and confusing as to why the very smart wizards only use the same special effect instead of doing the other special effects that would save them in a given situation, like how in fight scenes they only cast the same spell that just knocks you backwards,
Lastly, the ending.
It is so cheap. It felt like the entire trilogy was gearing up to one big send off, when suddenly SIKE WATCH THE 4TH ONE SUCKERS! In all seriousness, the entire final act is so contrived and convenient that its laughable.
MINOR SPOILERS
Jacob's arc in this film, while small, was about him being a good person. The entire premise of the ending is based on a person of true heart.
You'd think that Jacob, who has been nothing but haha funny fat guy the whole film, who the only non haha scenes he is in have been about his pure heart, would qualify for this and the foreshadowing would pay off, right?
WRONG
He gets ignored and all of the pay off is null. He could've not been in the movie, that's how little he does.
Secondly, SLIGHTLY MORE SPOILERS,
The blood pact between Dumbledoor and Grindelwald is a very important thing in this film. And yet, when the time comes, it is resolved in the most contrived, BS, The-writers-needed-it-to-happen way.
To summarize, this film had potential which it squandered. The story is poor, the pacing is off, and the ending is lackluster. Go watch a summary if you want the story.