I've never read any of her books. Cannot comment. My sister used to like them.
EDIT - IIRC her take is that the first Potter book is horrendously written but she gradually got better from there and that thinking she's an appalling writer in a world where Dan Brown exists is not fair.
I don't know. I've never read a Dan Brown book, but I have read several excerpts. Meaning I have some idea about his writing style, but not really about his stories (
this parody is great, even if it turns out that it's not accurate). I also relatively recently re-read the Harry Potter books.
Rowling's writing is bad. I don't know if it's extremely bad, but it is bad. The thing she's got going for her is world building, which in my opinion is not really (or at least not necessarily) about talent but that's another story.
The plots are really shit, but here the issue is that she's writing for children. Brown is writing for adults, allegedly, so should we shit on Brown while excusing Rowling because Rowling just wants to entertain pre-teens? Maybe, I don't know.
Take the first book, for instance. They want to find the philosopher's stone, which gives you immortality and some other stuff. It's Potter and the gang vs Voldemort. Wizard boss Dumbledore hid the stone behind seven
impossible challenges, each created by seven of his friends. It was emphasized how very impossible it was to get it.
So what are these challenges? Win a chess game, light a fire, solve a riddle, etc. Most of the stuff our heroes learned in the first week of their first year at wizard school, the chess game was barely four digit Elo, and the riddle stuff you'd find in a cartoon magazine. And that's half the book. Of course the challenges have to be piss easy when the kids reading it have to kinda follow along and the people actually solving them are around 10, but we're still left with the problem that seven of wizard boss Dumbledore's most trusted friends (several of them some of the most powerful wizards) are so confident in the impossibility of the challenges that they laugh off Potter and co when they warn of the incoming monster Voldemort (of course our wizard gang of 11 years old are the only ones who know what's going on, Rowling has after all read Bobbsey Twins).
Again, she's writing for children, so I don't know how to judge that. Her writing is shit, the story is bad but for kids, and the world building is exciting even if it's a ripoff of WW2.