The most productive tool to create Vector art from a bitmap image
Draw shapes and Trace will auto-fill them with best matching color composition - either single color or varying gradients
Use the Seed tool to create shapes that enclose chromatically homogeneous regions of the underlying image.
A tracing workflow always involves use of color picking tool to pick a color from the underlying image. Because it's such an important aspect of the process, Trace has closely embedded it in the interaction. As you manipulate the gradient controls, the stop colors are readily picked from the underlying image.
You get to draw and modify individual shapes using the interface that you would expect from any Vector Graphics editor. This is unlike other automatic tracing solutions that regenerate all the shapes after some parameter values are changed. This allows you to manually trace parts of the image, while you can use Seed tool at other places for automatic tracing. Then modify shape elements in isolated parts without affecting rest of the work.
Trace is unlike other automatic tracing solutions. Fully automatic trace utilities offer you to change only certain parameters and they regenerate entire vector art after each change. You do not have the freedom to manually edit a portion of the image, while run automatic algorithms on other parts. But with Trace that's exactly what you get. A semi-automatic tracing workflow that gives you very fine grain control.