Note that while the app and initial tutorial is free, there are in-app purchases for specific drawing tutortial topics that range in price from $2.99 to $6.99.
The introductory tutorials look very good and are accompanied by a somewhat unnecessary voice over that reads aloud the tutorial text that is on the screen. The sketchbook can be used freeform away from the tutorial. Unfortunately, there are two issues to contend with:
1. The app crashes a lot. I crashed it several times while drawing as well as when trying to delete a sketch.
2. The app attempts to teach you how to use different physical drawing tools (pencil types). However, using a finger tip (or even a special stylus) on the iPad’s screen is not a good analog.
I have a suggestion that should take care of both issues described above. Grab an actual piece of paper and collect the various pencil types and actually draw on a piece of paper while going through the app’s tutorial.