I'll keep this short.
The story of this movie isn't exactly one of the best since... it was pretty cliche with the "destroy evil with the POWER OF FRIENDSHIPPP!!" and, at the end, it seemed somewhat rushed. There wasn't much character development either.
As always, the art is great and the animation is top-notch and the music was very fitting for the particular scenes that they were used in. But all of this is just part of the norm for Hunter x Hunter.
What made this movie so enjoyable was the fact that it had many of the aspects that people look for in a movie that accompanies their favorite anime series.
A main factor of the enjoyment of this movie was the nostalgia. They brought back everyone's favorite quartet of all time and Gon's fishing pole :). They also reintroduced many of the characters that had not appeared for a long time in the main anime series such as Hisoka, Bisky, Wing-san, and Zuchi.
With the humor and teamwork of the characters, Madhouse really brought fans back to the old adventurous times, when the quartet would constantly work together.
The movie kept me at the edge of my seat, anticipating what would happen next.
I really enjoyed what this movie had to offer. 9/10