Book vs Movie
The book was absolutely terrifying for me. Until yesterday, I'd never seen the movie. With a new version of it coming out in 2017, I thought I should finally conquer my lifelong terror of clowns (which started long before I ever read It or knew Stephen King even existed). The movie...meh. Didn't strike the fear into my heart despite the clown. The Pennywise I imagined while reading the book certainly doesn't measure up to the Pennywise in the 1990 film.
Looking at It (the movie) 1990 vs 2017
warning - do not watch if you are scared of clowns
I will definitely be seeing the 2017 version. Pennywise looks a lot closer to what he does in my imagination. I expect I'll wait for this to come out on video then turn on all the lights and watch it. Because, well. CLOWNS. Actual, scary ass looking clown!