The change in authorial voice throughout the series as the children grew up was well done, though tailing off towards the later books as she never had the courage of her convictions to carry it through. Increasingly adult concerns entered the world, but only those concerns that were appropriate.
The first two books were finding their feet and genuinely children's books. The third book had genuine literary merit. After the thirds awards they became increasingly flabby and self-indulgent. Enjoyable and page turners but in need of an editor with the authority over JK to make her axe half the book. Very similar to the superstar director syndrome of producing a curates egg of a three hour movie within which is the body of a truly great 90 minute film screaming to be free.
What she did do outstandingly was to create a coherent world. To paint a character - albeit an archetype - with a couple of words. And a world people wanted to return to. This success contributed to the failure of her overarching project, as the shifting voice could not shift as far as it needed to without destroying the mise en scene that was her USP. 11-12-13 the characters and the voice aged naturally, but then their development arrested. Not to put too finer point on it they discovered the shrieking shack and didnt use it to get drunk and stoned and cop a feel.
