Having seen it for the first time, have a fairly mixed opinion.
The script could have used a LOT more work, there are info dumps galore and the characters flat out tell things that the film should show, sometimes they even do bth at the same time. Characters are thrown at the audience without giving them a chance to understand them, or even learn their names. It takes a long while to gain an understanding of them, by which time the plot has rolled on and left the audience behind. The scenes jump and jitter all over the place, jump cutting here and stringing together there. I personally struggled to figure out what was going on half the time because there was no room to breath between jump cuts. Jokes and references are littered throughout the feature, but few hit the mark, mostly due to the cheesy and over the top delivery that characterizes the "comedic" content. the premise could have been pulled off, well in fact, if the time had been taken to hammer out this script.
The music and singing talents are top notch, but they don't stick around for the dialogue, whose voice actors rarely resemble the singers, making most of the songs feel jarring and out of place. The lip syncing is usually good, but you can tell where new lines have been added over to replace the old long after the animation was done, sometimes in spots where there were none previously, which spoils the dialogue in sections. The main characters have decent vocal deliveries, but almost every other speaking character speaks in a stilted, emotionless manner which is out of touch with the context.
The animation was very good for the time, and it holds up. The characters are expressive and they move naturally and fluidly. The colouring looks nice and smooth, too. The camera work lets it all down though, with static shots, and no creative framing or angles to speak of, making it feel more like a play than a film. The backdrops swing between detailed paintings and almost non existent gradients, and cast shadows are rare.
Character designs are interesting. The cast consists of humanoid creatures descended from cats, rats and dogs, though I had to learn that fact from wikipedia because the narration that stated as such was removed from the edition I watched. The comedic characters usually have exaggerated, pointed features while the serious are more realistic, usually sporting pointed ears and muzzles. The designs are consistent and believable, but can make you feel a bit uncomfortable when things take on a more sexual tone, which happens both frequently and overtly.
The villain, Mok carries genuine threat in his presence and voice acting without dipping into silly levels of insanity. Unfortunately, his character is undermined by his tendency to info dump in every scene and bad lip synching.
This film is definitely not for children, Mok is seen snorting coke and smoking pot on screen, there are overt sexual references and the main characters are often referred to as "stoned" though their high is generally of magical origin. That being said, I don't think this is a film for adults either. The tone is too silly, and too disjointed to be taken seriously by adults, and the pace is to spastic to hold their attention when so many better rock and roll flicks are out there, leaving the film in an odd void, with no group that it can wholly appeal to.
I'm not sure where to put my final opinion on this film, I didn't particularly like it, but It was oddly engrossing and it definitely stood out, even if it was for all the wrong reasons. It's hardly a forgotten masterpiece, or a master anything, but its one of a kind and fans of animation and animation history should give it a watch if you have 80 minutes to burn, but try to track down the original version, as the American version redubs a swathe of the dialogue and removes many scenes, worsening the films bad qualities.