Kabuto Yakushi (pre Boruto)

Kabuto Yakushi (薬師カブト, Yakushi Kabuto) spent most of his life as a spy working for many different individuals, organisations, and countries during his life.

Bad Qualities

 * 1) For starters, he works for Orochimaru, who he later betrayed.
 * 2) He also wears glasses, when he can just use eye transplant. How is he not smart enough to do that?
 * 3) During the Chunin Exams, he befriended Naruto just so he can get his information, which is a huge stab in the back. Even worse, Naruto and his team trusted him and he told them that they were good.
 * 4) When Sasuke was placed in the hospital due to his curse mark, Kabuto broke in to his room, killed all the security guards and almost killed him,  Thankfully, Kakashi saw him and managed to stop him from killing Sasuke.
 * 5) He helped Baku kill Hayate Gekko, the proctor.
 * 6) During a filler arc, he forced Yukimaru to release all of his chakra, which caused the Three-Tails to go on a rampage
 * 7) He is a huge bully, one notable example is when he cut his own wrist to make Tsunade cower in fear, and then he slapped her and Shizune around like a huge punching bag.
 * 8) Also during that same fight, when Naruto used the Rasengan on him, he managed to use a scalpel to wound Naruto's lungs, which almost killed him. Thankfully, Tsunade healed him.
 * 9) Most of the time, he just comes off as a Dollarama version of Orochimaru, having similar powers.
 * 10) During the war, he reincarnated several dead people, including some heroes, to fight for him.
 * 11) Also during the was, Itachi and Madara broke out of his control and Itachi placed him under Izanagi, meaning that his jutsu being unbreakable was just a huge lie.
 * 12) He can be very whiny at times.
 * 13) He was responsible for the entire Fourth Great Shinobi War, meaning that he was responsible for many events, deaths and more.
 * 14) In the end, he sort of just became the ultimate Orochimaru fanboy.
 * 15) Despite being Orochimaru's most loyal henchman and his major role in the Fourth Great Ninja War which resulted in the deaths of many people, he isn't even punished for his crimes and is allowed to run an orphanage.

Good Qualities

 * 1) His design is great.
 * 2) His voice actors do a great job at voicing him.
 * 3) He was a much better character during the first half of the Chunin Exams, as he was shown to be more kind. He managed to stop Naruto and Sakura from peeking at the scroll during the Chunin Exams. If he didn't do that, Naruto and his team might have not sucessfully completed the exam and they would have been disqualified. He also teamed up with Naruto and his team get the second scroll. Together, they defeated the rain ninja and got the second scroll. When he parted ways with Naruto's team, he wished Naruto and his team good luck during the second round and he apologized to Naruto when he dropped out.
 * 4) During the Chunin Exams Finals, Hinata was coughing due to her not recovering from her fight against Neji, he saw her, healed her and saved her life.
 * 5) He told Team 7 where Sasuke was hiding at, and they managed to successfully find him.
 * 6) While he is mostly cold and heartless, he is seen to have a heart of gold, like during the Itachi Pursuit Arc, when he gave Naruto a book with all the intel that he and Orochimaru have gathered on Akatsuki over the years. When Naruto and the others can't understand why he would do this, he explains that it is a present for Naruto, partly to help Naruto in his own confrontations with Akatsuki and partly out of gratitude. He tells them how lost he felt after Orochimaru's death, having identified himself in terms of Orochimaru for so long, in the same way that Naruto was once identified in terms of the Nine-Tails. During the Tenchi Bridge mission, Kabuto heals Sakura's wound from Naruto as his thanks for their killing Sasori and thus weakening Akatsuki.
 * 7) After the war, he redeemed himself and now he is a much better character. In Boruto, all of his bad qualities are gone and he runs an orphanage, where he helps take care of orphaned children, following in his footsteps of his late mom.
 * 8) His backstory is depressing.
 * 9) The series wouldn't be the same without him.