The Rules of Magic is a fleshing out of the world of Practical Magic by way of the lives of the aunts from that book – Frances and Jet – and their childhood in the New York City of the 1960s. (I’m not actually quite sure the timeline works. It makes more sense if Practical Magic takes place in the 2010s, but the book was first published in 1995. It wasn’t a big issue, but it occasionally niggled at me.)
But I liked reading about their young lives in the city, and I always like reading about adventures in Manhattan in the 1960s, before it was glammed up in the 1990s. I enjoyed their run-down townhouse on the Upper East Side, I liked their witch shop in Greenwich Village. There are more fleshed-out male characters in The Rules of Magic than there were in Practical Magic, too. It might be a more solid book, in that way.
But it doesn’t have the over-the-top-ness of the prior book. And bits of it oddly took place in Paris, which, while one of the more feminine cities in the world (and one of my favorites), isn’t necessarily a witchy city.
If you enjoyed Practical Magic, you should totally follow it up with The Rules of Magic. I’m not sure it would stand on its own, though.