I went in with a pretty level head as a massive HP fan, and I wasn't disappointed.
Eddie as Newt was believable, but the choice of making him socially awkward did result in his scenes being stolen by everyone and everything around him because it was so regressive. Don't think that really mattered though. We coped with a pretty clumsy Harry Potter for 8 movies.
Tina was capable but not particularly compelling. Didn't have any chemistry with Newt, but Queenie and Kowalski made up for it. Thought Colin did well, as did Ezra and Samantha Morton even if she had very little screen time.
Cast aside, I felt the story worked. Made sense to use the escaping beasts to lead into a bigger plot and introduce us neatly into a new side to the magical world.
Grindelwald
as the big bad makes total sense and ties together this franchise with the original HP, though I probably would have dialled it up more to remind/inform what a threat he was. Non-fans aren't going to remember him from Deathly Hallows and the newspaper montage wasn't enough to get a real sense of threat.
Wouldn't say the plot blew me away with unexpected twists and thrills, but I feel like the appeal of HP has always been about the wizarding world it's in and Fantastic Beasts expands on it well. You want to see more of it.
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Loved it. And yes, Eddie ha acting was not THAT great.
he truly copied all of Grindewald's plans/work years later. 
New and Tina will never be loved. It's not in the cards, poor dat.