These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
From a modern perspective, his evilness is a source of some Values Dissonance: Jaffar actually comes and asks for the Princess's hand properly instead of just breaking into her garden, and even gives her a choice to 'command him'. He repeatedly refuses to rape her even if he could. But he's presented as the weaker, unmanly guy because of this. He shows noble intentions towards her for the first half of the film, and only turns murderous after he's gone nuts from her repeated rejections. Why she'd choose a bumbling prettyboy over a smart, sexy engineer and wizard, we will never know.
Conrad Veidt was the chick magnet of the film, something the producers and directors were very aware of. Of the other male leads, Sabu was a child star and John Justin hadn't made a single movie in his life. Veidt, on the other hand, had been a film legend for twenty years and had a large, swooning female fanbase (he would always make it to the top ten male actors list in British movie magazine polls of the time). Movie magazines at the time reported on the unusual enthusiasm he would inspire in female fans. He ended up receiving many letters from fangirls who said they would've definitely chosen Jaffar over Ahmad.