PS - I didn't know it was Miyazaki's debut film before watching, but looking back, I can definitely see his style.
The country, the architecture, the castle are all just so beautifully drawn. The fight scenes are incredibly fluid and energetic. It was made in 1979 and so, there are a couple of tropes that haven't aged well - specially the Damsel in Distress, but other than that, the plot is solid. The female characters, when they're present, aren't overly sexualized. It's just a very well made film. Above all, it's just so fun! The chase scenes are freaking hilarious. The villain is plain evil so you don't have to think about any morally gray areas or whatever. Just sit back, relax, laugh and have a good time.
Highly recommended.
Sorry, I knew you were talking about Clarisse, I should have added that I think they handled her well so I don't think it ages poorly. A movie in 1979 where the damsel in distress doesn't end up being the reward for the male protagonist is well ahead of its time. There are some shows where Lupin saying Clarisse is like a little sister means they're more likely to become a love interest lol.