I don't think the movie was the best thing ever, but I enjoyed it! Maybe I just set my expectations too high going into it, I don't know. I'll give it 4.5/5 because while I left the theater happy, I somehow wasn't completely satisfied.
Most of the small gripes I have with the movie are very specific towards my personal tastes and preferences, so I won't discuss that. The movie has a limited runtime of course, and won't be able to satisfy every single Mario fan in terms of their wish list.
The story was a bit generic, but I guess that's how Mario game's stories usually are, so I'm not gonna dwell on that too much.
While I can't speak for everyone, my theory is that if you are a fan of the Super Mario games, you'll enjoy this movie. If you are critical about movies however, you're definitely going to have some grievances. It's a fun love letter of a movie to Mario fans, but I felt it was a bit lacking in terms of excitement and writing.
Overall, I liked it, and am definitely going to pick it up as soon it comes out on dvd! And don't take my review too seriously, you may enjoy this movie so much you'll be grinning ear to ear the whole time!