I've read this book. It's definitely one of the more interesting and readable maths texts out there. I wasn't exactly sure I'd use the methods. Working as a mechanical engineer I probably go straight to numerical methods, or approximate things even more crudely and approximately than a mathematician's 'rough' work. Though "replace a complicated function with a rectangle" definitely resonated. Overall the impression was that it was full of great techniques for mathematicians and scientists puzzling out every bit of meaning they can from a situation whose true features aren't yet known.