The first half is amazing: a hallucinatory whirlwind of contemporary Uni life and the sleazy allure of Soho in the 60s. It has all the stuff Edgar Wright is good at: sparky dialog, energetic and creative choreography and of course, some ace music. I was entranced. And just when the film is going deliciously dark...
... It has all the stuff Edgar Wright is bad at: lousy effects, a tell-don't-show narrative, clunky exposition and a general sense that flashiness can replace nuance and intrigue. CGI stopped being scary this side of Jurassic Park and by the time the 30th jump scare rolled around, I was just a bit bored and felt like I was watching Dr Who.
Much like the Soho in the movie, you get seduced by the lights and sound at first, but soon realise it's actually all a bit tacky and shallow.