ColorBox is an ambitious app with a huge collection of writing implements, but without animations, a clearly-labeled interface or menus, it is unnecessarily hard to use. What ColorBox does well is to create a tool in which you can write nearly anything in any style or color you want, which for many people will be enough to overlook the glaring omissions in the app.
When you first open ColorBox, you can see at a glance just how many options there are. Tap any of the tabs on the left side of the screen and you can choose from one of dozens of colored pencils, pens, and other writing implements, each with a different thickness and color. The effect is no different from a radius slider and color wheel, but it is a lot more fun to look at. However, without menus on any of the pencils or pens, no animations when you tap them to know which you have selected, and a rash of different buttons and menus that are also not labeled, the app is hard to navigate in a number of different ways.
ColorBox is designed to provide a tactile digital writing and drawing interface. In some ways it works exactly as intended, but with a poorly designed interface, few tools for sharing or saving your work, and little organization, the app just doesn't have enough to recommend it over one of the many free alternatives on the app store.