Alison Lurie reviews the Harry Potter series in Pottery at The New York Review of Books. (Thanks to Educating Alice for the link.)
It's an interesting and thoughtful read; even if I didn't always agree with her. For example, I found this description of the four houses funny, but not entirely on target: "The student population of Hogwarts, like that of most high schools, is divided into jocks, brains, nice guys, and dangerous Goths." On the surface, amusing; but the Slytherins as Goths? Nope, doesn't work. But it did make me laugh.
Overall, I liked the essay because it approaches the series as the whole, also addresses the film, and avoids the now-tiresome "poor quality writing/ it's all about the marketing" arguments.
One final thing; Lurie, likes others, bemoans how the cast is getting "too old" for the roles they play.
Yes, it's true that sometimes actors play people their own age; but not always. It's not the only mark of a good, believable performance.
Yes, Ione Sky was playing her age in Say Anything; but John Cusack was already in his early 20s. Lindsay Lohan and Amanda Seyfriend played their ages in Mean Girls; but Rachel McAdams, playing Lohan's peer, is ten years older than Lohan. Tom Cruise was already 21 when he played teenagers in Risky Business and All the Right Moves. Three of the five Breakfast Club members were in their 20s. This game can, of course, go on and on and on.
The idea that the chronological age of the actor must be the same as the role they played, otherwise one must "suspend disbelief" is, to me, ridiculous. Case in point: Snape, as a classmate of James and Lily Potter, is 21 years older than Harry, so is in his 30s. I adore Alan Rickman. I firmly believe no one else could have played Snape half so well, and I cannot wait to see what he does with the role for the last two movies. Yet Rickman is 40 years older than the actor playing Harry Potter. I cannot recall any fuss being made about his being too old. Same for Gary Oldman, who is 30 years older than the kids rather than 21; David Thewlis is close to being the "right age" for a classmate of James Potter, but even he is 26 years older than Daniel Radcliffe, not 21.
In terms of the teenage cast aging and not being replaced: I find it remarkable that even the small roles haven't been recast. And the more interesting argument to me is not the "oh, the actor is too old!" but rather, how, now, does the actor's physical look match the person described in the book? Is that look still right? Because isn't that what Rickman, Oldman, and Thewlis were judged on -- not their ages, but did it "fit"? Was the performance believable? And, for the teens, the extra worry of, if a character is always described as short, yet the actor has become tall, what then?