I'm not a big Steven King fan and in my teens I read 3/4 of the book only to put it down and never return to it.
As for the films I can't say I'm a fan of either but the new one is OK to pass a few hours and has a few scares in there. The new Pennywise is a scene stealer whenever he turns up on screen though so worth the watch just for the scary clown.
Yes, the Pennywise was portrayed perfectly. I was pleasantly surprised, wasn't sure what to expect at first.