I enjoyed the book, though the movie was never as good as the book. Something tells me that this movie isn't supposed to mirror the book at all, though.
In the original movie, the childhoods of the main characters and their first encounter with Pennywise (the best clown) weren't as detailed as their adult lives and how they dealt with him then. I believe that this iteration is meant to tell the story of that first encounter and what it did to influence their adult lives, and make a real name entrance into horror, unlike the original did. (Of course, in its own time It was probably pretty spoopy. There's just different standards today.)
Pennywise is going to give nightmares to an entirely new generation of people. I just really hope this movie is done well, though.