Penultimate is fine for goofing around and jotting down a few quick items, but for serious note taking, get Notes Plus and a stylus. I've been using it for a couple of months now and it has replaced my paper notebooks at work. I sometimes scribble down a quick measurement or random thought on paper, but for meeting/design notes, everything is organized in one place. Using the close-up mode, you can write full pages of notes with ease.
I have no affiliation with the developer, but love the product. It is on sale today for $1.99. I'd grab it for that price.