What really scares you? What keeps you awake at night, or creeps into your dreams? For a large number of people I would imagine it is clowns - certainly it is one of my sister's top fears - that people find unnerving. Stephen King tapped into the prevalence of coulrophobia when he wrote his mammoth epic It, which has now been adapted into a blockbuster horror.

Telling the story of Pennywise, a child-eating entity that manifests in Derry, Maine every 27 years in the form of a clown, the book follows a group, loving known as the Losers Club, as they encounter Pennywise as children and adults. The cheeky approach the makers of this adaptation have taken is to split the story in half, with this film covering the Losers Club as children, and the adult strand to be picked up in a sequel film.

Pennywise is a fascinating creation, playing on one of the few lasting taboos through his violence towards young children, and it is a riot of a performance from Bill Skarsgård. It doesn't feel quite like this will have the lingering impact of Tim Curry's previous interpretation, but certainly Skarsgård's presence is felt throughout the film. The most effective use of Pennywise is in his first scene, which leads to the disappearance of Georgie, the ramifications of which power the film's more dramatic moments. This scene is modest, focused, genuinely chilling. No wonder it is so present in the film's marketing material. The rest of the horror feels far closer to that of a ghost train, but a very good one. If you've seen director Andy Muschietti's Mama, you'll know what to expect here. I really wish they had gone further with the Lovecraftian hints they give to Pennywise but maybe that will emerge in the sequel.

The film works more effectively as a coming-of-age story, closely resembling the likes of Stand By Me and ET. The haunting of the group by Pennywise punctuates scenes of swimming in gorges and sweeping shots of the group on their bikes. For the most part the film could have been plucked out of the 80s heyday of Spielberg and Amblin films. It trades on the warm nostalgia that Stranger Things so successfully tapped into last year and can't help but raise a well earned smile. In fact this feels less like a film and more like we are binging on a TV show, with the episodic nature of the narrative playing into this. The film deals remarkably successfully with the trauma of being a teenager with exceptional strong performances from Jaeden Lieberher as Georgie's grief-stricken brother and Sophia Lillis' Beverly. In particular Lillis is the presence who lingers at the end of the film, and her story touches on real world trauma that has an unexpected impact.

The film does feel a tad overstretched. Very good horror has a leanness to it, with the fat surgically removed. So It is not a very good horror. But it is a very good theme park ride, hence the film's already colossal success. You can watch the film in comfort that little will truly harrow. It'll make you jump but, beyond an early effective scene, little will leave an impression. But it is wonderful that a horror film is a mammoth hit, even if it is worrying for the clown profession.