"Jekyll and Hyde" claims to be a rock musical from the "Rocky Horror" school of low-budget cult musicals. Even fans of "Rocky Horror" and its cult-movie ilk ("Shock Treatment," "The Apple") will admit that these kinds of movies aren't "good," per se. The acting isn't the greatest, the film-making is a bit awkward... but still, they have something-- a fun, camp sensibility, an imaginative bizarreness, some catchy songs.
Unfortunately, "Dr. Jekyll and Mr. Hyde" isn't bad in a fun-campy-cult-movie kind of way. It's bad in the "we have absolutely no idea of how to make a movie" kind of way. It's like four buddies in a band--with absolutely no knowledge of or talent for scriptwriting or film-making--pooled together $1000 and roped in their friends to act in the movie version of their song cycle. The results are really only fit to be viewed by their family and friends. A total lack of narrative coherence, hilariously bad dialogue and acting, disposable characters with no motivation, excruciatingly awkward editing and really, really poor cinematography... this movie has almost nothing going for it. It seems almost mean to criticize the particulars, because this is obviously not a film that any professionals were involved with. Ideally, it would never have made it into the video stores in the first place.
I will say that the songs aren't bad. They're reasonably catchy, the musicians seem talented, and the lyrics are standard rock-musical fare. As a mostly-sung stage show (presumably set in 1885 Britain, rather than "present day Los Angeles," justifying songs like "London Fog" that are otherwise totally illogical), "Dr Jekyll and Mr. Hyde" probably wouldn't be so bad. As a really, really ineptly made movie, though, it's godawful. Unless you personally know the filmmakers and are curious what they were up to that one summer, stay away. And if even you do know the filmmakers... you'll probably still be disappointed.