Comment by utopiah

Exactly, if you don't enjoy sketching concepts, think via diagrams or need to write in order to think then a PockerBook is good enough.

If, like me, you clarify your thoughts by physically writing (not typing) or sketching, then the ability to do so without distraction, moving a piece of text of the page, changing the position of a box in a complex diagram... then it's definitely worth the price IMHO.