I absolutely loved this movie! I haven't played many Mario games besides Mario Kart on the Wii but I enjoyed almost everything about the movie. The way they portrayed Mario and Luigi's relationship as brothers was very sweet in my opinion. You don't see siblings who get along well very often in film at all. The only thing that bothered me was the comments made by that little blue star thingy over the lava, but they didn't have much screen time.
Also, the animation was gorgeous. And the soundtrack! 10/10
I definitely recommend watching this movie.