How is different from inertia expressions?

Noodle works with a lot of properties including paths, on a point by point basis which you can easily customize. Noodle also works with parented properties, which lets you soften the motion of a "child" layer. Noodle is calculated very differently from those types of expression and is more advanced and customizable. Also, the tool panel lets you turn noodles on and off, bake them and edit them very quickly and intuitively without diving into expressions.

Can you bake the results?

Hell yes. You can bake to keyframes/expressions. You can choose to bake inside the work area / the layer's bounds.