I will talk only about the errors of the series .. Arc by Arc
Although the beginning paints well and forms the friendship relations of which the main cast will be everything that consists of the examination itself is badly planned, to start all the characters do not seem to have empathic emotions with respect to everything that is happening in the same exam, nobody is unfazed or feels some fear corresponding to death, if I compare it with the whole cast that was raised and the situations in the Chunnin exam in Naruto this part HxH is too short, I could also talk about the end of the exam the hunter is hypocritical in the sense that they had raised this idea "No matter what happens we will continue with the exam until the end" but when they reach the tournament part in the end they complement it with "You can not kill the opponent" here everything goes relatively "Good" but when Killua kills the opponent they send everything to take for ass and approve the others in such a simple way, all the effort of the people who died to love complete the exam they sent him to take for ass for that detail.
2) Tower of Heaven
A whole arc where Killua and Gon go in search of skills, their premise is their problem, because it is basically that, a focused arc only to start making "Complex" the fights and make the show "Deep", the arc entirely dense, not passable or entertaining, simply dense and tedious, the fights of that arc are worth nothing because Gon and Killua are entirely protected by the plot armor of the moment so you know that they will not lose or die, therefore there is NO RISK, that means "boring". The arc is entirely bad
Decerebrate action with a protagonist Gary stu to summarize things ... Kurapika skips the rules of the Nen that were established a back arc, you can increase the powers as he wants, He has unlimited access to the whole bar of powers of Nen, does not have any reflection after killing Uvogin because he had previously established that from his point of view everything he does is correct, Togashi fills Kurapika with unlimited weapons and powers after taking all one to create such a complex system of powers ... Shit
4) Greed Island
The tower of heaven made worse; This arc is basically canon filler, you can skip it and it will not change anything, just take care to know that "Gon and Killua train their powers in a world of video games" because from then on the villain is the worst of the series in general , the bomber is forced into this arc only to create "drama and tension" .. All this arc is the worst shit
5) Quimera ants
Very good the arc entirely, the whole series was prepared for this moment and it is excellent, it has its criticable things as the Asspull of the nuclear bomb of Netero or that eliminated all the development of Meruem giving it "Amnesia" only to lengthen the arc still more in a more insufferable way ..
The arc totally shits the consequences of the chimera ants (Revive Gon), the idea of Alukka was not so bad since it had rules but AGAIN togashi loves to fuck his own rules and makes Killua know the only way to get the wishes WITHOUT CONSEQUENCES ... To end the arc with Gon looking for his father in the world tree, Gin tells him the message of the work in general "That what matters is the trip, not the final destination" the message would have meaning if Gon had learned something in his trip through the whole series, but you know what? GON NEVER LEARNS ANYTHING, IS THE SAME START TO THE END ... With this proposed you can imply that everything that happened the series is a nonsense that even in its last moments can unite its history with coherence to the message of the work
The work is anticlimactic, it breaks all its proposed ideas, the protagonist never learns anything, the work is worth only in a single arc of 6 principals arcs,
the direction and the music make the anime mediocre even when the script entirely becomes bad.