This movie was so bad that it actually made me took the time to write this (spoiler-free) review.
Even tho I am a huge fan of Hunter x Hunter, I knew I shouldn't put too much expectation onto this film. Having seen the Phantom Rouge one, I figured this movie would be disappointing as well, but I could have never imagined it could reach this level of just plain badness.
The story itself is already an overly used plot, but the way it progressed only made it dumber. Hunter x Hunter is known to have revenge-focused storylines - all of them very well paced, packed with lots
of action, emotion and character development. The Last Mission does no justice to this at all: it not only builds a very boring story around a new (and also boring) villain but forces it to some very lacking fights and underwhelming speeches that turned out to be just outright cliché.
Even when the plot is already enough to make this film a forgettable one, it also presents us with VERY poorly written characters - not only the new ones but also the ones we love so much -, most of them being part of the movie just for the sake of the fans who want to see them and not serving to the plot AT ALL.
Now it isn't all negative points with The Last Mission: the sound, the music and the animation were correctly used, although the character design and the color palette were much more simplified and a little bit off in comparison to the anime series.
Overall, all of these things somehow merged and came to be the incredibly boring movie I'm reviewing now. Feel free to watch it and see that for yourselves.