It's big. It's everywhere. But just how good is it?

Something is seriously amiss in PotterWorld. Ron and Hermione never stop snarling at each other, and Harry is so bad-tempered that he keeps having to yell at them in CAPITAL LETTERS. Muggle-style teenage hormones are kicking in at last.

The longest Potter adventure to date takes an age to get going. All right, there's an exciting encounter with a Dementor in the first few pages, but it takes 180 pages just to get to Hogwarts, and it's 370 pages before Hagrid shuffles into view. Can Rowling's amazing comic invention be showing signs of fatigue?

I've been a fan of all the books so far, but this one sags. The first few hundred pages are taken up largely with bafflingly bureaucratic struggles between Dumbledore's Order of the Phoenix (the wizards who oppose Voldemort) and the timid officials of the Ministry of Magic. Harry is threatened with expulsion (yeah, right), and half the magical world doesn't even believe Voldemort has truly arisen. The Ministry (whose London offices, inventively described, signal a brief return to form) has decided to keep a close eye on the school. And who can blame it? Once again children suffer horrific injuries in the course of a normal term: hit in the face with bludgers, savaged by magical creatures... the blood runs thick and hot. Dumbledore clearly couldn't run a sandpit.

The Weasley twins work overtime in this glum hormonal stew, as Harry's damp romance with the vacuous Cho Chang moves sluggishly on. There'd be precious few laughs without Fred and George's joyous habit of road-testing prototypes from their magical joke shop.

It's a good job I have my own magical powers. About half way through I sent my magical eye (just like Mad Eye Moody's) to the end of the book to see what happens. Yes, a "major" character dies, but though Harry rages and weeps (unconvincingly - his range as a written character stays well within Daniel Radcliffe's tiny range as an actor) I was unmoved. Rowling may care passionately for the victim, but she hadn't managed to transfer her enthusiasm to this reader.

Worse of all, Harry's misunderstood boy hero routine is starting to grate. Judge by our extract, right, which shows Harry facing a criminal court.