Glad you liked it. I was a bit worried, actually, because Rider Haggard isn't for everyone. Some people don't care for the somewhat old-fashioned style of writing.
It's also kind of remarkable that a novel written by an Englishman at that time has a cast of characters who are all black Africans (apart from some bit-part Boers who play a very peripheral role in the story - if not in history), and doesn't feel the need to insert a white point-of-view character. I do like Quatermain, but in some of his books you get the feeling RH only has him there because he has to, and it's the Africans he's interested in. In those stories Quatermain isn't much more than a glorified narrator watching the action. I'm glad he finally found the courage to do without him, even if only for one book, as he really wasn't needed for this story.
Nada herself is a bit of a let-down, though. She's very much a plot macguffin and near permanent damsel-in-distress. Haggard would refine his African Princess archetype in later books, coming up with the Kick-ass Maiwa, and the scheming Mameema, who are both much more interesting and less passive characters with a lot more agency. A good start, though.