If you are interested in seeing a side story about the MHA characters post the super-serious battle in the latest season, and especially with a lighter setting, this "movie" might just fit the bill. For me, it worked like any other MHA piece.
The plot is about a superhero battle, just with a card game spin to it. The animation is pretty much the same in terms of quality, and there's ample action and humor to back the proceedings. Nothing unpredictable about the plot, and even though it feels like a marketing strategy for an actual card game, this special is harmless and good fun for MHA fans. Intro and outro songs are the same as in S6.
Action scenes are well designed, especially keeping the card game backdrop in mind. While it might not leave you overwhelmed with some complex plot twist, or teary eyed, this is just a fun wholesome special episode which caters to fans who just want to see their favorite heroes happy and having fun after a rather fighting a dark and soul-shattering war.