This is such a smoothly controlled movie on the whole that there's incredibly little to complain about across the board, though it's fair to say that the film's use of CGI does verge on the excessive from time to time.
Though the visual effects used to realise Pennywise's various forms make a lot of sense and are generally well-deployed, it's frustrating when Pennywise is occasionally smeared with unnecessary digital distortions, usually when he rushes towards the camera at one of the kids.
The intent is presumably to make the clown's movements seem otherworldly and unsettling, but the digital smear just looks more cheap and tacky than anything.
That's thankfully the only real issue, so here's everything the movie gets totally right...
Stay at home dad who spends as much time teaching his kids the merits of Martin Scorsese as possible (against the missus' wishes).
General video game, TV and film nut. Occasional sports fan. Full time loon.