Mads was awesome and should have been Grindlewald from the start or kept Colin Farrell, who was also very good in the first one. The whole cast is great and story has an interesting premise.
However, they should have let Newt Scamander be his own cool branch of HP for kids and had the story of Grindelwald and the first Wizarding war as a separate, more adult cool HP branch. In trying to appeal to everyone from kids to adults to elderly, they made a huge boring mess that appeals to no one. And that's a shame because both branches could have been classics.