IMO, the graphic violence in the P&tB books was much less effective at conveying horror than Frank's more circumspect approach. Not surprising really since any good writer knows that nothing they can describe is as terrifying as what the reader can imagine.
For comparison, there's a scene in on of Herbert's Pandora books ('The Jesus Incident' I think?) that has always stuck with me as being particularly effective in showing something particularly gruesome happening to someone...without actually showing it. It's been a while, so I forget the details, but at some point a female character is brought into a room euphemistically called "the flower garden" (it's actually where all the horrific genetic experiments are kept. Think 'The Fly II' and multiply it by a thousand.)
You don't get the lurid details of what happens after they close the door on her...but you're left with your imagination spinning in some very unpleasant directions and what she does the next time she appears only adds to it.
Compare that to the robot in the prequel books making human soup as an artistic expression...well, there's just no comparison.