The app isn't as flashy or robust as SketchBook Pro or Autodesk's other iPad offerings, which is partially to its credit--controls are simple, and a tutorial is easily accessible within any section of the app. Unfortunately, you're limited to a single layer of art and one background layer imported from the Photos app.
When you first launch the app, you're brought to a blank canvas. There are toolbars on three sides, with Autodesk's signature silver circle in the bottom center to banish and call up those at will.
The left side is dedicated to a variety of brushes; the right, a color picker; and the bottom contains a mish-mash of document settings and brush variation.
Ink comes with seven brushes, each with its own variable speed and line width. Unlike an app like Procreate, however, you can't adjust either--only the line's maximum size--and as a result, the brushes, while neat, don't quite achieve the same smoothness as those in other apps. There are also two variable-width erasers.
Ink's big draw for artists will be its export settings: The app allows users to export flat PNGs of up to 11,500 pixels wide (around 101.5MB) via Dropbox or iTunes File Sharing; you can also export drawings up to 4000 pixels wide (approximately 12.6MB) to the Camera Roll or via email. Not vector, but certainly large enough to create a rough sketch before bringing it into a computer to ink and perform touch-up work.