The lines are everything you can imagine - from bold, fat, irregular strokes to thin lines. But it's still a ruling pen, so it can (and will) surprise you. What I love the most it the dynamics of the lines. It's almost like they were living their own life. Of course, when you put extra effort to it, you can keep them under control (more or less), but that's not really the point of using a ruling pen for me :)