William Friedkin always was a lifeless hack. And while it sometimes pays dividends (The French Connection), more often than not it's To Live And Die In L.A. or, worse, 1992's dim-witted, reactionary Rampage he ends up lensing. No, Friedkin's is no gift.

And The Exorcist? Well, you see, Mark Kermode adores The Exorcist. Ask him. The best film ever made. That tells you where he's coming from, which makes his BFI Modern Classic altogether more surprising, being the sober piece of journalism it is. Indeed, because the story behind the picture is so strong, he will no doubt manage to convince the young and the impressionable that its unavailability on video is an artistic outrage. Moral, maybe, but hardly artistic.

Whatever its technical problems (and there are many), the obstacle Kermode never addresses in these info-packed pages is the picture's whole tenor. Unlike The Omen it's no roller-coaster ride, its intentions loftier; a Serious Film. But only so much as you buy into its po-faced demonology. There is no metaphor in those frames, no irony; Blatty and Friedkin take it on trust. And, maybe if you're a nun, devout Catholic, or just plain wired, you can afford the purchase. Outside of the religiously disadvantaged, however, it's hard to see just why anyone would take it as anything more than sloppy - and in the exorcism itself, cheesy - video fodder. It's not as imaginatively unsettling as The Haunting or even Jacob's Ladder, and certainly not as flat-out scary as Clayton's The Innocents. Kermode's claim that it "slips from the realms of mere cinema to the arena of magical incantation" is laughable.

His book is lavishly illustrated throughout, exhaustively researched (it traces back to the real-life inspiration for Blatty's novel), and well written. It is also a great deal more rewarding than Friedkin's film.