Well, to be honest, 160ish pages into Order of the Phoenix, they haven’t got to Hogwarts yet. There’s been the little matter of Harry’s trial to consider, though a lot of time has been spent introducing various significant things for later in the book/series (#12 Grimmauld Place, the Ministry of Magic, Kreacher, Sirius’s little brother, the mysterious “heavy locket that none of them could open”*, etc).
Once you get over Harry’s surliness, there’s also a lot of interesting presentations of character. Sirius comes across with more bitterness than in the film (which makes sense), Harry shows the beginnings of maturity – provided he gets a few minutes to himself to stop and think about how he feels rather than just reacting (which he does far too much of – though he’s not the only one), misunderstandings and arguments arise because of realistic situations (e.g. it doesn’t feel contrived that Harry should be holding Ron’s badge at the point where Hermione rushes in).
Of particular note is Mrs Weasley. One thing about having seen various fanfiction, it gives you an idea of how other people see different characters**. Views are somewhat divided over Molly Weasley – is she a loving parent, or a smothering busybody determined to run her children’s lives? I suspect the answer depends on whether you are a parent or a teenager yourself. Though not a parent, I feel the scene with the boggart (depicting sundry dead Weasleys), and the mention of Gideon and Fabian Prewett’s heroic deaths, tells you all you need to know about Molly. Yes, she can be overbearing, but ultimately she’s desperately frightened of losing her family again.
Don’t worry, Molly. Your moment will come.
* Of all the wierd and dangerous trinkets they find when cleaning out the house, I almost think the music box that nearly puts them all to sleep, or the snuffbox that bites Sirius would be more interesting Horcruxes (horcruces? horcruxii?). Probably not really Voldy’s style (but then, I can’t imagine him in Ravenclaw’s tiara, either).
** Including the Draco In Leather Pants phenomenon, that even the author has expressed bemusement over.