As it's hard to talk in a meaningful way about such a long series (there's over 30 novels in the series, plus manga adaptations and a prequel series, set three-thousand or so years before the beginning of VHD during the Human/Vampire Wars), I'll talk a little bit about the most-accessible form the series takes, the two film adaptations.
To the filmmakers' credit, though, they did do a good job capturing D's essential character, without which the film would have been a total failure.
Bottom line, I liked the move all right, but it wasn't what I wanted in a VHD film.
The second film, titled VAMPIRE HUNTER D: BLOODLUST, however, I absolutely loved. It's everything you could want in a VHD movie adaptation and an entertaining film in its own right, even if you know nothing about the character or the series.
Based on the third VHD novel, titled "Demon Deathchase" in English, and separated from the first film by almost sixteen years, BLOODLUST was intended specifically for simultaneous theatrical release in both Japan and the US, with both Japanese and a US-based production companies collaborating on it. The difference in budget, technology and attention to the source material shows big-time.
First, the film is gorgeous. Unlike the generic designs of the first film, this movie's designers took care to capture the visual aesthetic Yoshitaka Amano created with his covers and illustrations for the novels. They also captured perfectly some of the more surreal visuals that Hideyuki Kikuchi describes in his prose. Beyond the designs, the color palette was both marvelously well-suited to each scene and surprisingly varied, which was no easy task considering much of the film takes place either at night, in darkened ruins or in a half-dead post-apocalyptic wasteland. Honestly, I was very impressed with that aspect alone.
Second, the story - it was only loosely based on the novel, but instead of being a partially-accurate recap like the first film, it was more that a different storyteller told the same tale in their own way. It wasn't 100% accurate to the novel, of course, but it did an excellent job of capturing the feel and spirit of the novel while feeling like something almost-original. Some people have complained that the story is thin and while that's valid to a degree, they're missing the point of the the story: it's the characters that make it interesting; the plot is merely the vehicle that drives them forward. And to be honest, the plot of the novel itself is not particularly deep, compared to some of the other books, either.
My one real complaint about the film is a technical one: it has horribly-mixed sound. The dialogue and BGM/SFX were at such vastly different levels you have to keep constantly adjusting the TV's sound to hear the dialogue, then quickly turn it back down to keep from blowing your eardrums out. It was annoying and took me out of the experience multiple times.
Overall, though, that complaint aside, I give it a 90 out of 100 and definitely recommend it to anyone who is a fan of VHD, action/horror movies or just beautiful animation in general..