I find that a moleskine seems too nice to use up with my chicken-scratch quick notes. I tend to like the feeling of crumpling up a post-it after completing the task on it. I can't cleanly do that with a moleskine. Tearing the page out of those things really makes it less pristine and formal-looking.

Yeah, I bought some molesinke cahiers for the same purpose. Simple and lightweight, and they take a good beating.

Still, I don't think I'd buy them again. Seconding Yan's sentiment, a notecard (or napkin!) is all you need in moments of inspiration.