Most of the praise for Paranormal Activity seems centered on director Oren Peli’s achievement in making an effective thriller on an infinitesimal budget – $15,000, to be precise, though I doubt that includes whatever Paramount paid for its brilliant marketing campaign.

It’s a wonderful story, encouraging to indie filmmakers hoping for their own big break – Paranormal was stuck in cinematic purgatory until a print arrived at the desk of DreamWorks co-founder Steven Spielberg – but it speaks only in passing to the strength of the movie itself, which deserves a more muted celebration.

That’s not to say Peli’s debut isn’t chilling, at least in fits and starts. But it’s far from groundbreaking. Its central conceit – the device of the handheld camera, used to give sensational material the feel of cinema vérité – is by now familiar, having been employed with varying effectiveness in movies like The Blair Witch Project (1999) and last year’s Cloverfield.

Some have argued that Peli’s stylistic flourishes seem more authentic, suggesting, I suppose, that shabbier cinematography and shoddier sound produce a more genuine article. In that sense, Paranormal has more in common with Blair Witch than Cloverfield – it looks like the work of an amateur, if only superficially.

Yet the handheld camera itself seems more of a contrivance here, not an integral part of Peli's story. In Blair Witch, three student filmmakers ventured into the Maryland woods to make a documentary about a local legend. In Paranormal, Micah (newcomer Micah Sloat) begins filming to confirm his girlfriend Katie’s suspicion that an evil spirit is lurking in their home. Micah gets his evidence, enough to persuade even the most recalcitrant skeptic, but keeps up the shooting long after its usefulness been exhausted. Why? Well, if he didn’t, there’d be no movie.

Micah is a day trader, we’re told, though he never seems to work, except when it comes to analyzing his home movies. Even as events far beyond the realm of human understanding unfold before his eyes, he ludicrously insists he’s in control, and it’s then that his obtuseness begins to seem suspiciously like a plot device. Against the advice of a psychic (Mark Fredrichs), he consults a Ouija board, and after watching it spontaneously burst into flames – never a good sign – he remains mostly unfazed.

Katie (Katie Featherston), on the other hand, is a longtime believer in ghosts and demons – she’s been haunted on and off since childhood – and grows more hysterical by the day, with good reason. Something is after her, and until Micah decides to play hero, it’s content to make minor household adjustments, like playing with the bedroom door. Once antagonized, the mysterious spirit turns from idle mischief to full-blown malevolence.

There are few surprises in Paranormal Activity, from its beginning to its ho-hum ending. But there are enough jolts in the night to keep you alert, and otherworldly intrusions that make the skin crawl. These contribute to the requisite sense of dread, but too much of the creepiness feels arbitrary. What does the demon want? Katie. Why does he want her? Who knows?

It’s only natural to fear what we can’t understand, so it’s no shock that Peli’s invisible bogeyman has struck a chord with some moviegoers. He’s the ultimate home invader, toying with his victims for 80-plus minutes before tiring of the game and unleashing a few seconds of uncontrollable fury. It’s over in a flash, leaving us momentarily shaken but not necessarily stirred.