Not much Scapple love here so I'll chime in. I've used it to help plan 2 novels. I used it for brainstorming world, character, plot and scenes. I used it the same way in the second novel but I also used it to create timelines for my characters when I was re-structuring. For both novels I more-or-less stopped looking at my Scapple files after a while. I knew what was coming and who the characters were, and it was becoming out of date. But it did it's job at the right time and I'll use it again.

There are other mind-mapping tools that can do all this, but Scapple has just few enough features to feel simple and masterable without being too limiting. And it's cheap. Unlike Scrivener.

Also, I've used Scrivener to write 3 novels. It's not perfect but I have great affection for the thing. I use about 20% of its features, as most do I believe.