Having trouble remembering any movie I saw in a theatre that I disliked except for a Wrinkle in Time, but I'm absolutely sure that there were several before it that I walked out disappointed from.
But gosh that movie. Such wasted potential. And it was clear Disney expected it to be a humongous hit with audiences from how they promoted it and how it even got a place in one of those projection shows at Disney World alongside actually tested and true live action Disney movies. It was simply too mediocre to be that success though. Bad pacing, subpar acting, rather poor visual storytelling (I didn't even realize the third kid who showed up had been in the movie's intro until my mom pointed it out after I asked "how does he know these two?")... Just a mess.
I guess Fantastic Beasts was kind of middling too, but that's only on second viewing at home, I rather liked it in the theatre.