The original manga series is known in Japan as one of the earliest manga series of the mystery genre. Its more kid-friendly, well-known counterpart Detective Conan (aka Case Closed) only began serialization 2 years after this one. In the early days, Kindaichi was better received in Japan than the latter, as shown by its sales numbers. Much of its fans loved it for its whodunit mysteries, which I would explain below. In the late 90s, due to Detective Conan pandering to a wider audience, Kindaichi's popularity slowly plummeted, and now even though it is still considered a classic mystery series, it could no longer regain its former glory.
Onto the anime adaptation, it is definitely a pity that this anime series did not receive any release in the western world by any distributors. Online fansubs are also rumored to be rather terrible, with the first 20 or so episodes being watchable only. I would say that the series deserves a larger audience, because of the reasons that I would explain now.
Story: 9
The anime series of Kindaichi does not have an actual continuous story unlike Detective Conan. Each individual murder case takes up about 3-4 or even 5 episodes to resolve, usually involving a murder of about 3 people, 4 if longer, but rarely does it elevate to 5 or more (though there do exist such cases). One could argue that with the introduction of the criminal mastermind Takato Youichi in the 3rd season of the anime, the story became continuous, but I would argue that one could still watch each case individually or in a non-linear fashion, and would still not be confused.
Dissecting into the structure of each case, a Kindaichi whodunit mystery follows the same formula: Kindaichi goes to a place, meets a few murders, solves them, end of story. However, each case does not simply become boring because of this. Kindaichi's cases are well-known for their unique tricks used by the murderers in each case. The tricks may appear simple, but still have their own elements of surprise.
Furthermore, I would also recommend the murder cases to people who enjoy tragic, sad backstories. The murderers in Kindaichi's cases all usually have a well-justified reason why they want to kill their victims. And while you would probably not agree with their way of resolving things by murder, you would probably feel a sense of sympathy for them after you listen to their backstories.
Art: 6
As a 90's production, the art definitely leaves room to be desired. The animation does not flow well occasionally, and some characters may appear deformed in certain episodes. Nevertheless, the art should not bother you if you watch Kindaichi for the story.
Sound: 9
Kouji Wada does a great job at composing the soundtrack for Kindaichi. Each scene, whether be it conveying sadness, anxiety, happiness, has a well-composed piece to it. The two tracks that are particularly memorable are the one usually played when a body is found called "Jicchan no Nami Kakete!", and the one played during a heart-beating, nervous scene called "Nazo wa Subete Toketa!".
Character: 8
The main character, Kindaichi Hajime, is an IQ 180 genius who acts goofy all the time, but when needed can show a sense of justice. Along with him are his childhood friend Nanase Miyuki and the police officer Kenmochi Keibu. The series, being composed of standalone cases, do not show much character development for its main cast, but the characters interact well with excellent chemistry in each case.
Along with the main cast are a number of characters (the victims, suspects and the murderer) in each case. Like any other whodunit series, the characters need to be unique, well-fleshed out for an audience to truly enjoy the cases. Luckily, Kindaichi Shounen no Jikenbo does that well, providing enough screentime for each character before his/her ultimate fate.
Conclusion: 9
The series is not perfect, but I would still recommend it if you are a hardcore detective fan who loves long, well-planned murder cases with intriguing tricks and sad (sometimes tragic) endings. I would say it certainly deserves a lot more popularity and I wish that a distributor would meet up with this piece of gem and release it.
*Side-note: A list of my personal recommendations if you are too lazy to watch through all of the 148 episodes:
The Murders of the Fudou High School Seven Mysteries (Episode 1-3)
The Murders of the Gentleman Thief (Episode 10-12)
The Murders of the Trickery House (Episode 18-20)
Kindaichi the Murderer (Episode 24-27)
The Murders of the Magical Express (Episode 33-36)
The Murders of the Snow Demon (Episode 37-39)
The Murders of Reika's Kidnapping (Episode 47-50)
The Murders of the Computer Lodge (Episode 74-77)
The Murders at Snow Village (Episode 111-114)
The Murders of the Russian Dolls (Episode 139-143)
