The Toei features of the 50s, 60s, and 70s are obscure in the US, which is a shame. This film in particular is a lot of fun.
Yes, the animation is limited and almost TV-quality. However, it all has a Seuss-like charm blended with Looney Tunes anarchy. The few musical numbers there are manage to be catchy (you'll have the jazzy "Ali Baba" stuck in your head for days) and there are wonderful gags galore. The climactic battle is great cartoony fun.
Though I was attracted to it because it was a film Hayao Miyazaki, one of my all-time favorite directors, had worked on before he made it big with Nausicaa in the 1980s; however, on its own merits, this is a delightful comedy. Not a classic or a masterpiece, but it's fun for fans of anime and animation.